Replace OAuth implementation with a more recent one

We now use https://github.com/tim/erlang-oauth/. Since it is just one
file, oauth.erl, the file has been added to the support/ folder of
mod_oauth, instead of making it a sub-dependency.

Fixes #730
mod_base: Fix infinite loop in controller_page

When the resource had its page path set to "/", the calculation of the
request page path would fail, causing a redirect.
skel: Fix blog styling of navigation bar
build: Dont send Travis CI success notifications when it did not fail
install: Fix query syntax error due to missing comma
mod_survey: Work around mod_survey initialization error

Prevent database deadlock by doing the queries async after a delay. Not
the most beautiful solution, but it appears to work.

Fixes #734

See issue #497 for the discussion on the "proper" solution.
mod_survey: Add comment about schema initialization workaround
mod_survey: Slightly better workaround for survey initialization deadlock

no spawn or delay, just use a clean DB connection.
doc: remove stray doc file for unnamed template.
doc: add minimum description of mod_admin_stats.