Modify net_plugin's logging initialization

Change net_plugin to ask for its logger vs pushing a logger in to the logging framework. This allows net_plugin to honor the logging.json configuration easier. Non-contentious change: no longer can you log-level-net-plugin to change the debug level; use the common logging.json to set the log level. More contentious change: network logging is not added by default, it must be placed in to logging.json

Fix UDP double tap in fc's UDP send_to fast path

P2p optimize retry 2408

Configurable Tapos for txn-test-gen

Add a configuration for the "lag" off of the head block for the reference block for generated transactions.  This allows us to test Tapos to HEAD and tapos to LIB as well as many other options

solution for issue #2390 

Fixes to code coverage build.

1824 fix memory wrapping bug and add unit test cases

#2390 only start syncing on a notice from the peer, and reset the state if no peers available to continue syncing

Elementary OS support added

Fix for eos #2160

Eosio build darwin, boost version verification

Eosio build: 7 gigs of ram requirement and other fixes

Merging master to avoid conflicts

Merging master before creating PR

Update resource_limits_private.hpp

#2284 validate threshold > 0 for authority, add test case

fix for eos #2364

add unit test case for #2193(double billing)

Docs clearly state this is not a safe call from a signal handler.

Merging master

bancor has wrong README