Underpinnings of a better single-process, no-dependancies Cortex.

[tomwilkie]

Starting to do the refactoring needed to build a better local/no-dependancies experience:

• Move some flags code around, add ability to parse lists of strings, look for an address on both eth0 and en0 so Cortex will start on a Mac.
• Start adding yaml tags to config structs; local config will need different sets of defaults for the flags, and instead of changing the defaults (which we can't do for backwards compat) I though we could load from form a yaml file?
• Wire up the lifecycler code so it was use inmemory store, and make inmemory store "global" so the querier, ingester and distributor modules all get the same one.

[tomwilkie]

Also see weaveworks/common#132

[gouthamve]

Looks good! Mostly looks like it's just moving the flags package to a new subdir and the updating the references. I'm a little concerned about Linux where the interface name is not one of the defaults. My linux systems have wlp2s0 in my laptop and enp2s0 on my desktop.

[tomwilkie]

I'm a little concerned about Linux where the interface name is not one of the defaults. My linux systems have wlp2s0 in my laptop and enp2s0 on my desktop.

I've added the ability to override the interface names in yaml; don't want to put lo in there as a hard coded default, but for the "local" config file we could include that.