Use APIPATH_MAXLEN from the right module

This fixes an AttributeError.

Change-Id: Ic76f42d7fbd6c0dd0fbdf2ccf464e8fff80b11cd
fix errors/warnings in tests

sphinxext tests reference paths that don't exist. this patch
corrects it.

Change-Id: I6a9355a53e2f72de7eab17fc117334843ff8d369
Fix broken sphinx tests.

Change-Id: I2c2046b4ef31c78731f25f3b8e579b05ca0953fb
Add support for manually specifying supported content types in @wsmeexpose.

Closes-bug: #1271317
Change-Id: Ia28a912f4444a6ff77b1feaf2ea6440b0c738e86
Fix tox configuration.

-   Make sure tox-tmpl.ini and tox.ini are consistent

-   Avoid coverage 4.x

    Coverage 4.0a1 CLI is not happy with the commands we use in the unittests.
    Avoiding it for now.

Change-Id: I6976d4a94358692f5cb9570f672f6dd985f5d1b1
Minor documentation edits

Change-Id: I0f8049241ffd870a4dac405fa0ca53fb122f2181