svn: make hooks safe and fully backward compatible. - fixes problem with older protocol hooks that doesn't support given methods. - in cases of older SVN we should simply skip, and not fail.

hooks: allow skip hooks seperately for git and svn

git: fixed code after version upgrade

git: bumped version to 2.16.3

hg: fixed code after version upgrade to 4.6.0 release

dependencies: bumped mercurial to 4.6.0

dependencies: dropped pinned wheel dependency.

dependencies: bumped zope.interface to 4.5.0

dependencies: freeze few libraries for better rhodecode-ce compatability.

dependencies: use all lowercase dependency names for better ordering of auto generated files. - allows easier diff of dependencies across projects.