Add travis scripts
Attempt to #ifdef the ARM dmb behind a test for armv7

closes #6
Update .travis-ci.sh

Add oUnit to Travis depends
turn the copy of barrier.h in lib_test into a symlink
Merge branch 'master' of github.com:avsm/shared-memory-ring
fix typo in ARM v4 define (rmb->wmb)
Merge branch 'master' of github.com:djs55/shared-memory-ring

Conflicts:
	CHANGES
Merge pull request #8 from avsm/master

Fix ARM compilation and add Travis scripts.