Fix out typemap for dolfin::la_index
Remove use of deprecated functionaity in some tests.
Update code in demos using deprecated interfaces.
Update system test for new assembly sytax.
Merge branch 'garth/test-updates-for-interface-changes' into garth/fix-issue-119

Conflicts:
	test/unit/fem/python/Assembler.py
	test/unit/la/python/Matrix.py
Merge remote-tracking branch 'origin/garth/test-updates-for-interface-changes' into garth/fix-issue-119