Change deriving target of gpio.rs

Fixes hackndev/zinc#51
Merge pull request #55 from bharrisau/issue-51-2

Change deriving Eq target of gpio.rs. Fixes #51.
Allow non-snake-case functions in ioreg. Fixes #52
Updated init/uninit to zeroed/uninitialized. Fixes #53
Removed #[start] from app.’s, as it’s never used.
Updated todo for app_systick demo (it’s still broken)
Detached GPIO from GPIOConf (as it should have been in the first place).
Removed forceful inlining
Fixed toolchain naming (TOOLCHAIN now includes trailing '-')
Remove TOOLCHAIN_LIBS_PATH

The runtime library is now loaded explicitly in
RUNTIME_LIB env variable.
Merge pull request #60 from farcaller/compiler-rt

Remove TOOLCHAIN_LIBS_PATH
Break libcore -> rust dependency to allow builds with r/o mounted thirdparty.
Merge pull request #57 from farcaller/refactor-gpio

Detached GPIO from GPIOConf

Reviewed-by:
Extracted cross-build rustic flags to allow native builds.
Add '--test' flag if building for test.
Added run_tests helper that runs all tests in passed compile_rust rule.
Added 'as_dylib' helper.
Added the very basic platformtree macro code with tests.
Added 'rake test' to travis build.
Allow PIC in native builds.