Fixed 'close' packet bug, organized imports in [transports.base]
Fixed XHR_Polling error responses
Fixed probe transport error message
Useful websocket errors
Removed 'binary_type' parameter
Transport closes now return upgrade errors
Enforce timestamps and ensure they are unique
Bumped version to 1.2.1-beta
Merge branch 'release/1.2.1-beta'

Conflicts:
	setup.py