add --format json output enhacement to flash and certificates commands

[umbynos]

flash and certificates commands output now can be set to json 🥳
By running FirmwareUploader firmware flash -b arduino:samd:mkr1000 -a /dev/ttyACM0 --format json something like this is returned:

{
  "programmer": {
    "stdout": "Set binary mode\nreadWord(addr=0)=0x20007ffc\nreadWord(addr=0xe000ed00)=0x410cc601\nreadWord(addr=0x41002018)=0x10010305\nversion()=v2.0 [Arduino:XYZ] Dec 20 2016 15:36:43\nchipId=0x10010005\nConnected at 921600 baud\nreadWord(addr=0)=0x20007ffc\nreadWord(addr=0xe000ed00)=0x410cc601\nreadWord(addr=0x41002018)=0x10010305\nAtmel SMART device 0x10010005 found\nwrite(addr=0x20004000,size=0x34)\nwriteWord(addr=0x20004030,value=0x10)\nwriteWord(addr=0x20004020,value=0x20008000)\nDevice       : ATSAMD21G18A\nreadWord(addr=0)=0x20007ffc\nreadWord(addr=0xe000ed00)=0x410cc601\nreadWord(addr=0x41002018)=0x10010305\nChip ID      : 10010005\nversion()=v2.0 [Arduino:XYZ] Dec 20 2016 15:36:43\nVersion      : v2.0 [Arduino:XYZ] Dec 20 2016 15:36:43\nAddress      : 8192\nPages        : 3968\nPage Size    : 64 bytes\nTotal Size   : 248KB\nPlanes       : 1\nLock Regions : 16\nLocked       : readWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nreadWord(addr=0x41004020)=0xffff\nnone\nreadWord(addr=0x41004018)=0\nSecurity     : false\nBoot Flash   : true\nreadWord(addr=0x40000834)=0x7000a\nBOD          : true\nreadWord(addr=0x40000834)=0x7000a\nBOR          : true\nArduino      : FAST_CHIP_ERASE\nArduino      : FAST_MULTI_PAGE_WRITE\nArduino      : CAN_CHECKSUM_MEMORY_BUFFER\nErase flash\nchipErase(addr=0x2000)\ndone in 0.852 seconds\n\nWrite 16328 bytes to flash (256 pages)\nwrite(addr=0x20005000,size=0x1000)\nwriteBuffer(scr_addr=0x20005000, dst_addr=0x2000, size=0x1000)\n\r[=======                       ] 25% (64/256 pages)write(addr=0x20005000,size=0x1000)\nwriteBuffer(scr_addr=0x20005000, dst_addr=0x3000, size=0x1000)\n\r[===============               ] 50% (128/256 pages)write(addr=0x20005000,size=0x1000)\nwriteBuffer(scr_addr=0x20005000, dst_addr=0x4000, size=0x1000)\n\r[======================        ] 75% (192/256 pages)write(addr=0x20005000,size=0x1000)\nwriteBuffer(scr_addr=0x20005000, dst_addr=0x5000, size=0x1000)\n\r[==============================] 100% (256/256 pages)\ndone in 0.103 seconds\n\nVerify 16328 bytes of flash with checksum.\nchecksumBuffer(start_addr=0x2000, size=0x1000) = a16c\nchecksumBuffer(start_addr=0x3000, size=0x1000) = 684a\nchecksumBuffer(start_addr=0x4000, size=0x1000) = 4179\nchecksumBuffer(start_addr=0x5000, size=0xfc8) = efe8\nVerify successful\ndone in 0.014 seconds\nCPU reset.\nreadWord(addr=0)=0x20007ffc\nreadWord(addr=0xe000ed00)=0x410cc601\nreadWord(addr=0x41002018)=0x10010305\nwriteWord(addr=0xe000ed0c,value=0x5fa0004)\n",
    "stderr": ""
  },
  "flasher": {
    "stdout": "Flashing firmware /tmp/fwuploader/firmwares/WINC1500/19.6.1/m2m_aio_3a0.bin\nFlashed all the things\n",
    "stderr": ""
  }
}

The same applies to flash command.

Along the way I solved a 🐛 in #57

[silvanocerza]

There are some small changes to do but the rest is alright.