Changing incorrect documentation

The original comment on set_session said to return true or false
depending on whether the session was saved or not. In reality, this
method MUST return the session id in order for #commit_session to set
the cookie data properly.
Remove specific version code from Lint

 * Too easy to miss during updates
 * Required format unchanged
 * Closes #501
Merge pull request #500 from aocole/patch-1

Changing incorrect documentation
Bump version and add release notes to README