rez release: check for valid svn directory when testing if svn release mode is available
Refactor RezRelease base class so that init now only takes a path, and move other other arguments to RezRelease.release().
Add RezReleaseUnsupportedMode.
Rename RezRelease to RezReleaseMode
Refactor SvnRezRelease so that it serves as a better model for implementing new release modes.
rez-release help: Replace references to 'SVN' with more generic 'VCS'.
change quoting used in install.sh so that values such as 'gedit --wait' do not cause errors.
Change rez-svn-print-last-tag to use methods on rez_release.SvnRezReleaseMode
Add a mercurial release mode.