Add coverage target to Makefile
Add coverage target to Makefile

Use gover to combine coverage reports and upload to coveralls
Requires env variables to be set appropriately.

Signed-off-by: Dave Tucker <bfcdf3e6ca6cef45543bfbb57509c92aec9a39fb@socketplane.io>

socketplane/socketplane,mrjana/socketplane,socketplane/socketplane,mrjana/socketplane,mrjana/socketplane,socketplane/socketplane