Check whether PLT file is outdated or not

Erlang's dialyzer creates a PLT file for static analysis. Creating
such a file takes a long time, hence it's preserved between builds
on the build bots.

It can happen that the PLT file is outdated and needs to be
regenerated. This commits adds the automated regeneration.

Change-Id: I1194c8db44a662821e8f55d435ee2e34d4c61707
Reviewed-on: http://review.couchbase.org/41814
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Volker Mische <volker.mische@gmail.com>
MB-12112 Add option to add search paths to unit test run script

It's now possible to add additional search paths for beam files via
the "-f" option. It expects a format that can be used in ERL_FLAGS.

This makes it possible for geocouch to add additional modules needed
to run the unit tests. It's about test helpers residing in the the
`test` subdirectory of the geocouch apps.

Change-Id: I339ff146a4920db0d59a8eafb02cf910e2dc02a1
Reviewed-on: http://review.couchbase.org/41762
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Volker Mische <volker.mische@gmail.com>
Make geocouch's dialyzer happy

geocouch uses some of the couchdb functions, hence some type specs
need to be adapted in order to make the dialyzer run on geocouch
happy.

Change-Id: Iaea98815ac8670d7222c181f6d11d406ff5295a9
Reviewed-on: http://review.couchbase.org/41951
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Sarath Lakshman <sarath@couchbase.com>
Merge remote-tracking branch 'upstream/master'