Testing database dbsrv should be moved to a separated config

[l4u]

eredis_pool:start() tries to connect to a localhost redis database because of the dbsrv configs
if there is no local redis server, there will be a connection error.

[hiroeorz]

I separated config file "./test.config", and changed Makefile
$(REBAR) skip_deps=true eunit -> ERL_FLAGS="-config test.config" $(REBAR) skip_deps=true eunit

If you want to use custom environment, create config file and exec eunit.

ERL_FLAGS="-config yourconfigfile.config" ./rebar skip_deps=true eunit

Thank you.