[FEATURE] Add Call#wait_for_end, which blocks until the call ends and returns its end reason
Merge branch 'develop' into feature/feature/wait_for_call_end
[UPDATE] Function correctly with Punchblock 2.0 headers interface

* Need to maintain BC with regards to symbol access and downcasing/substitution of dashes
[BUGFIX] Deal with non-string header names
[CS] Punchblock 2.0 stuff is now on its' develop
[CS] No need to serialise SSML output documents here
[DOC] Changelog entry
Revert "[FEATURE] Do a stack dump when receiving USR1"

This reverts commit dd4d3927621721cd53c6ab5c024f2323db4a8390.
[UPDATE] Bump to 2.3.5
Merge branch 'release/2.3.5' into develop
[UPDATE] Use RubySpeech 2.0
[UPDATE] Use PB 2.0's call-uri attribute
[DEPS] Remove ruby_gntp
[BUGFIX] Removed unnecessary Mocha reference from generated plugin.
Merge branch 'feature/punchblock_2.0' into develop
Merge pull request #324 from adhearsion/feature/gen_remove_mocha

[BUGFIX] Removed unnecessary Mocha reference from generated plugin.
Merge branch 'feature/wait_for_call_end' into develop

Conflicts:
	CHANGELOG.md
More descriptive error message
[FEATURE] Enable the console on JRuby
[BUGFIX] Call loggers should be deleted after a call finishes