improved move units

Phaser only moves sprites when within the update method.
Hide action overlays when unit is moving.
After all player's units have moved, start next turn and reactivate
player units.
working on end of turn procedure

Added a couple of helper functions
Start removing Roman units after turn 5
PIXI (which is built into phaser.min.js apparently) is having problems
with its _bindings objects, perhaps due to my extending Phaser's
objects?
More NPC action

Wait for NPCs to finish moving before setting active player unit, with
more helper functions for common tasks regarding tile locations.
Improved Roman Moves

Improved movements of Roman units towards the south, stopping on the
southeast coast and not abandoning London early.
Also, don't waste time moving removed units.
New Britton City Image
New Saxon/German City Image
Better Saxon City Image
Cities can change hands

Now cities can change ownership, with updated imagery.
Also change board tiles
Start moving Saxons

Very rudimentary...
Also, removed units need to be removed off the board
Give Saxons full moves
code refactoring, use defaults object
Merge branch 'master' into gh-pages