Add TI Tiva C controller support.

Currently supported:
 - GPIO
 - System clock configuration
 - UART TX with polling
 - Timer support with polling
 - Platform tree support
Merge pull request #209 from simias/master

Added TI Tiva C controller support.
Add tiva_c to travis' build matrix
Merge pull request #254 from simias/master

Add tiva_c to travis' build matrix
Sample app for the hd44780u LCD driver on tiva C
Merge pull request #253 from simias/lcd

Sample app for the hd44780u LCD driver on tiva c
Merge pull request #256 from 0xc0170/master

Ioreg: fix warnings in parser (eq fn)
Node - RegPrim - operate on borrowed type - dont move fix
Core::Option and Result - namespacing fix
Copy is opt-in, see rust PR #19644
k20 - Option namespaced fix int the app layer, plus one in cortex m3
AstBuilder::path_all grew another argument
ioreg::node: Add Copy impls for enums
ioreg: Produce Copy impls for register types
volatile_cell: Add Copy impl
platformtree: FnStyle is now Unsafety
Fix various Option constructor references
ioreg: Resolve shadowed lifetime variables
Fallout from rust #19448

String concantenation is now a bit more painful. Perhaps there's a
better way?

https://github.com/rust-lang/rust/commit/0669a432a2e09ad08886cb2138dbe9f5d681fb7f
SlicePrelude is now SliceExt