Refactor BitcoinModule to extend AbstractBitsquareModule
Remove UI test runner classes and .fxml files

These classes were used during individual screen creation but are now
effectively dead test code.
Introduce #close hook
Simplify references to stylesheets
Remove use of final modifier on local variables
Remove commented code
Refactor ViewLoader construction in src/main
Handle IOException within ViewLoader#load

Prior to this change, all callers of ViewLoader#load were forced to
handle the (checked) IOException declared by the #load method signature.
This resulted in a significant amount of duplicate handling logic where
nothing more than logging the error occured.

Failing to load a view represents a catastrophic error in the
application; i.e. it is not something that can be handled in any way
other than shutting the application down, fixing what is broken and
restarting the application. For this reason, any IOException raised
within ViewLoader#load is now caught, wrapped and re-thrown as an
(unchecked) RuntimeException. This will be handled by the platform's
UncaughtExceptionHandler, and a dialog will be raised to inform the user
that a fatal error has occured.

As a result all try/catch blocks around calls to ViewLoader#load have
now been removed, making for tighter, more readable, and easier to test
code.

In the future, the distinction between errors that are programmatically
recoverable and those that are catastrophic (typically developer errors)
will be used to determine whether methods in the Bitsquare API throw
checked or unchecked exceptions.
Introduce FatalException

Rather than throwing a generic RuntimeException for fatal / catastrophic
exceptions (which are typically due to developer error) throw
FatalException.
Introduce ViewLoaderTest and FxmlResource interface

Tests basic loading of FXML resources via the ViewLoader API. Also
introduces the FxmlResource abstraction, an interface which the
Nagivation.Items enum now implements. This simplifies the process of
testing, e.g. in this case testing a non-existent resource without
having to add a bogus value to the enum itself.

Note the @BeforeClass logic necessary to initialize the JavaFX platform.
This is necessary in order to avoid "Toolkit not initialized"
exceptions. See http://stackoverflow.com/q/11385604 for details.
Remove use of Profiler from BitsquareUI

Also remove Profiler#initScene, whose body was entirely commented out
and therefore dead code.
Add comment for each major step in BitsquareUI#start
Rename AWTSystemTray=>SystemTray and remove statics
Refactor SystemTray
Move ActorSystem shutdown logic out of SystemTray
Ignore Structure101 files
Remove cycle between SystemTray and BitsquareUI
Relocate BitsquareUI#getPrimaryStage
Begin separation of JavaFX GUI and seed node CLI
Remove static access to BitsquareUI#getPrimaryStage

 - Bind BitsquareUI#start's primaryStage for DI
 - Statically inject primaryStage directly into Help and Popups