Normalize version

[KeyWeeUsr]

ref #4861

Standardized format for version in X.Y.Z[.dev0+hash] shape. Can be turned off for a release with env variable KIVY_RELEASE.

There were necessary changes in parse_version, otherwise it won't accept such a version. It might break the previous kivy.require() in some cases.

Hopefully there won't be much appveyor script can break in this and as discussed before, since this change there'll be necessary to force install each master version, because there'll be no way how to compare the versions because of the hash (unless MICRO changes):

from packaging.version import parse
parse('1.9.2-dev0.24012017.e4d8cb9c') < parse('1.9.2-dev0.25012017.a9d5d756')
# True
parse('1.9.2-dev0+e4d8cb9c') < parse('1.9.2-dev0+a9d5d756')
# False