Introduce new Erlang/OTP 17.0 convenience function oauth2_response:to_map/1
Refactor oauth2_response_tests:to_map_test/0 to a property-based PropEr test
Merge of IvanMartinez work, PR #47
Merge branch 'IvanMartinez-api_docs'
Merge pull request #42 from synlay/feature/oauth2_response_to_map_convenience_function

Introduce new convenience function oauth2_response:to_map/1
Prepare 0.5.1
Add functions for implicit grant

Added `authorize_password/7` to aid in implementing `implicit_grant`(4.2)
To validate a public client(just validate the redirection_uri) and a
authenticate a user and issue a token use:

```erlang
{ok, {Ctx, Auth}} =
    oauth2:authorize_password( CLIENT_ID
                             , CLIENT_SECRET
                             , CLIENT_REDIR_URI
                             , UNAME
                             , UPWD
                             , USCOPE
                             , CONTEXT ),
{ok, {Ctx, Response}} = oauth2:issue_token(Auth, Ctx),
```
Roll a new tag
Pass around the right AppCtx
Merge pull request #11 from kivra/master

Update to kivra:master