added policy applicability clause
documenting style and compatibility concerns
Adding a versioning policy
Merge pull request #255 from pulp/mhrivnak-version-scheme

Adding a versioning policy
Merge branch 'devguide-2.0' into mhrivnak-applicability

Conflicts:
	docs/sphinx/dev-guide/policies/index.rst
revisions based on review
Merge branch 'devguide-2.0' into mhrivnak-compatibility

Conflicts:
	docs/sphinx/dev-guide/policies/index.rst
improvements based on review
Merge branch 'devguide-2.0' into mhrivnak-docguide