Added http_proxy support to HttpSchemeHandler.
Also use http_proxy for MvnSchemeHandler.
Merge branch '0.7.x' into 0.7.x-proxy-support
Updated Changelog.
Merge branch '0.7.x' into 0.7.x-proxy-support

Conflicts:
	ChangeLog.txt
Merge branch '0.7.x-proxy-support' into 0.7.x