Revamped SessionService
Added SessionRequestFilter
Merge branch 'master' into feature-sessions
SessionFilter is now both response & request filter
Added documentation to SessionService
Added tests for SessionService
SessionService now throws on non-existing session
Added documentation in SessionFilter
Added SessionFilterTest stub
Added more tests for SessionFilter
Merge remote-tracking branch 'origin/feature-sessions'

Conflicts:
	src/Niysu/Server.php
	src/Niysu/Services/SessionService.php
Changed line endings