[WIP] Improve dialyzer command

So far:

* The default warnings have been changed not to suppress the standard warnings and the `race_conditions` warning has been removed as it may cause problems[1].
* Change how PLT building/checking is carried out so that there is a single plt (that does not include the project files, only the deps) that is updated when deps change.
* Improve formatting of unknown types/behaviour/functions so that the warning is not prefixed by ":0:".

Todo:

* Build a better PLT (need to add ALL application deps, not just the rebar project deps).
* Add option not to check the PLT.

[1] http://erlang.org/pipermail/erlang-bugs/2014-July/004518.html