Refactored pre_commmunication_layer tests to match recent changes/fixes.
Merge pull request #40 from SkewedAspect/bug-ccase-com-layer-tests

Communication Layer Test fixes.
Added doc target.
Fixed errors that prefented doc from running.
Removed unused modules.

Not exactly a documentation change, but makes documentation make more
sense if unused modules are removed.
Cleaned up doc output for pre_data.

Added some specs to some unspeced functions and removed dividers that
were pointlessly cluttering the output.
Shored up docs for the entity layer app.
doc cleanup in the pre_comms app.
Removed comm layer from a deps list.

Deps are those that need to be retreived, which makes rebar get
confused when it can't retreive it.
Merge pull request #39 from SkewedAspect/bug-mw-doc-creation

Bug mw doc creation
Bumped rec2json version used.

Rec2json had a couple of bugs making life more difficult than it
should have been. Those have been fixed in the newest version, so we should
use that.
Merge pull request #41 from SkewedAspect/bug-mw-bump-rec2json-version

Bumped rec2json version used.
Bumped rec2json req'ed version. Again.
Added vector:zero/0 and quaternion:identity/0, return identity from quat:unit/1 when norm is small enough, and added rec2json custom type support.
Added pre_physical and pre_physical_store.
Migrated simulation logic from pre_physics_rk4 to pre_physical.
Renamed 'Delta' to 'TimestampUsec' to make its contents clearer, added a spec, and changed it to call into pre_physical:simulate().
Corrected first step sim_evaluate starting value for Spin.
Corrected return values for rec2json type conversion functions.