Fixed RAC 2.3 compatibility issues

Test passing on RAC 2.3 and RAC 2.1.8
1) Added RAC_DEBUG_SIGNAL_NAMES environment variable to TEST scheme, so RACStream -setNameWithFormat: works
2) didSubscribeWithDisposable expects RACCompoundDisposable instead of RACDisposable
Merge branch 'master' of https://github.com/lawrencelomax/LLReactiveMatchers into rac_2_3_compatibility
Merge pull request #23 from glyuck/rac_2_3_compatibility

RAC 2.3 compatibility issues