Change stop order in riemann_SUITE
Run tests on 17.1 and against Riemann 0.2.6
Switch from Rebar to erlang.mk
Mark clean-proto as PHONY
Fetch deps when building app
Keep all as the default target
Relax deps in rebar.config
Compile .proto file with +debug_info
Cleanup test suite
Add a way to query Riemann asynchronously

Using `katja:query_async/{1,2}` and `katja:query_event_async/{1,2}`
Riemann can now be queried in a non-blocking way. The query results will
be send to the inbox of the calling process.
Update README
Add sentence to docs
Add CT include
Add coveralls
Improved ecoveralls integration
Better .coverdata generation
Cleanup katja_writer entity creation
Add async data-sending functions
Update Makefile
Expand connection_SUITE