Expose network information to GUI cleanly

This commit introduces io.bitsquare.network.ClientNode--an interface
whose name and structure will surely change--as a simplistic abstraction
over TomP2PNode that allows for exposing information to the "Network"
tab of the Preferences section of the GUI without actually requiring the
injection of TomP2PNode and other tomp2p internals into the GUI layer.

Changes to 'network' and 'msg' packages:
----------------------------------------

 - Move ConnectionType enum from test into main tree, and expose
   ClientNode#getConnectionType.

 - Both ClientNode and TomP2P are now available for injection. Both
   types are bound to the same TomP2P singleton instance. Note
   especially how NetworkPreferencesViewCB now receives a ClientNode
   instead of a TomP2PNode.

 - Restore package-private visibility to BootstrappedPeerFactory

 - Remove no longer necessary TomP2PNode#getPeerDHT

 - Expose getter for BootstrappedPeerFactory#bootstrapState

Changes to 'gui' package:
-------------------------

 - NetworkPreferencesViewCB has been simplified. All no-op methods have
   been removed, and the class now simply implements JavaFX's
   Initializable interface as opposed to Bitsquare's own ViewCB
   hierarchy, because the latter is not actually necessary (no caching
   is required for the data handled by this controller, etc.

 - In order to make the above possible, PreferencesViewCB now tolerates
   adding non-ViewCB child controllers.

 - NetworkPreferencesPM has been removed (perhaps temporarily), in an
   experiment to see "just how simple" CB controller classes can be.

 - Text fields in NetworkPreferencesView have been renamed.

Notes:
------

The data that now shows up in the "Network" tab is no longer formatted
as it once was; values are essentially nothing more than their #toString
representations. Again, this can be tweaked further, but leaving things
in this raw state provides an opportunity to discuss the current
presentation model approach, ViewCB hierarchy, etc.
Introduce customized JOptCommandLinePropertySource

This temporary subclass introduces the same change proposed in
spring-projects/spring-framework#693, and should be removed when that
pull request is merged and made available.
Use #ofType in commandline parsing for type safety

 - Remove Node#getPortAsString; it is now no longer necessary
Use BitcoinNetwork vs. BitcoinJ's NetworkParameters

BitcoinNetwork now supports a #getParameters method that returns the
BitcoinJ NetworkParameters instance associated with the given
BitcoinNetwork enum label (e.g. TESTNET.getParameters() returns
TestNet3Params, etc).

BitcoinModule#BITCOIN_NETWORK_KEY and #DEFAULT_BITCOIN_NETWORK have been
moved to BitcoinNetwork#KEY and BitcoinNetwork#DEFAULT respectively.

Customzing the bitcoin network to use on the command line has been
improved. Values may be upper or lower case (e.g. "testnet", "TESTNET"),
and the value passed is converted to the correct BitcoinNetwork enum
value with the new EnumValueConverter class.

Finally, a BitcoinNetwork instance is now made available for injection
by BitcoinModule as opposed to binding a NetworkParameters instance. All
injection targets (constructors) throughout the codebase have been
updated to reflect this change, and the result is cleaner, enum-based
processing everywhere possible. And where it's necessary to drop down to
BitcoinJ's NetworkParameters, that's easy to do by calling
BitcoinNetwork#getParameters.
Polish FeePolicy

 - Convert static fields to final instance fields

 - Remove commented code

 - Rethrow any AddressFormatException as a BitsquareException instead of
   logging and returning null (doing so would cause NPEs in BitcoinJ
   internals).
Merge branch 'cbeams'

* cbeams:
  Polish FeePolicy
  Use BitcoinNetwork vs. BitcoinJ's NetworkParameters
  Use #ofType in commandline parsing for type safety
  Introduce customized JOptCommandLinePropertySource
  Expose network information to GUI cleanly

Conflicts:
	src/main/java/io/bitsquare/msg/tomp2p/TomP2PNode.java