Allow using Firebase RDB emulator with Firebase client

[yuri-sergiichuk]

This PR fixes the handling of the Firebase RDB emulator endpoint. The DB URL may be of two formats:

• the https://<database-alias>.firebaseio.com DB URL points to a remote Firebase RDB;
• the http://<local-ip>:<local-port>?ns=<database-alias> points to a local Firebase RDB emulator.

For the latter, the ns part stands for namespace and is effectively used by the emulator as a way to determine the local database instance to be used. Prior to the improvement, such a query in the URL was not handled properly and it was not possible to connect to a specific database thus one should have to just guess which database would be used (from what I understood, if 127.0.0.1 IP address is used, the DB name would be 127, for localhost I was not able to determine which one is used).

The PR also bumps the Jackson version to address security vulnerability.

[codecov]

Codecov Report

Merging #166 (cb2be82) into master (28748bf) will increase coverage by 0.26%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##             master     #166      +/-   ##
============================================
+ Coverage     60.14%   60.41%   +0.26%     
- Complexity      210      213       +3     
============================================
  Files            93       93              
  Lines          2366     2382      +16     
  Branches         43       45       +2     
============================================
+ Hits           1423     1439      +16     
  Misses          932      932              
  Partials         11       11              

[dmdashenkov]

@yuri-sergiichuk, LGTM as soon as all the checks pass.