Dispatch a blinker signal on scope change, instead of raising a warning

See https://github.com/idan/oauthlib/pull/265 for rationale.
In brief: raising any exception blows the stack, which is
inappropriate for a non-error state.
Allow invalid token_type_hint.

Invalid token_type_hints should be ignored. This looks to have been
broken in 6ffcc4f2ae6b66e42c1f58b6de634fe969b473a0
Merge branch 'scope-change-signal' of https://github.com/singingwolfboy/oauthlib into singingwolfboy-scope-change-signal

Conflicts:
	oauthlib/oauth2/rfc6749/clients/backend_application.py
	oauthlib/oauth2/rfc6749/clients/legacy_application.py
	oauthlib/oauth2/rfc6749/clients/web_application.py
Wrap OAuth2 tokens in a OAuth2Token class.

The OAuth2Token class allows for easy checking of scope
changes and might be extended with further convenience
methods in the future.

Additionally, the Warning raised on scope change will now
include a ``token`` parameter with a full OAuth 2 token
in case scope change is fine, which ideally it should be.

Users who don't want to catch a warning can instead
check the boolean token property ``token.scope_changed``. Note
that the warning must first be disabled by setting the
environment variable ``OAUTHLIB_RELAX_TOKEN_SCOPE``.
Add blinker to tox.ini
Tidy up makefile and add contacts meta data.
Fetch docs version from oauthlib.__version__
Docs updates recovered from a broken git repo.

Draft release process doc to try force myself into more
structured releases in the future.

A few initial notes on how to report errors.

Added a few common exceptions to the FAQ.

Removed supported versions from feature matrix. They are all
available in setup.py metadata.

Move JWT tokens to grant types where it (confusingly) belongs.
Merge branch 'allow-invalid-token-type-hint' of https://github.com/RodneyRichardson/oauthlib into RodneyRichardson-allow-invalid-token-type-hint
Fix minor merge artifacts and python 3 tests.
s/lepture/evonove/
Move changelog into its own file.