1D Facet numbering fix

Fix 3 different points at which Fluidity facet numbering is used in 1D
to use UFC numbering instead.
Add test of bcs on interval mesh

Sets the left hand end to zero and the right hand end to one and solves
the identity equation with a right hand side equal to the coordinate.
Merge pull request #144 from firedrakeproject/1d-facet-bug

Switch to UFC facet numbering (rather than Fluidity numbering) for 1D.