Branches containing a slash break v4 branch endpoints

[vetruvet]

The encoding of branch names in API v4 has changed from unencoded slashes to encoded as "%2f". As such, getting branch information for a branch like "env/production" is broken in the latest version.

Ironically this means #86 basically needs to be reverted.

Removing the str_replace call in Repositories fixes the issue for me but I'm not sure if there are any other places where this needs to be done.

[fbourigault]

Could you open a PR to fix this? If we find other places later we will do more fixes.