GMT instead of UTC. Closes #83.

Response date fields are now using GMT instead of UTC (the two are
equivalent but the HTTP de-facto standard is all about GMT).
Merge branch 'gmt' into develop

Conflicts:
	CHANGES
GMT instead of UTC. Closes #83.

Response date fields are now using GMT instead of UTC (the two are
equivalent but the HTTP de-facto standard is all about GMT).
Merge branch 'gmt' into develop

Conflicts:
	CHANGES
missing space  caused Sphinx warning