PETSc 3.5.1 with intel 2014b

Plus dependencies
Needs https://github.com/hpcugent/easybuild-easyblocks/pull/446
and https://github.com/hpcugent/easybuild-framework/pull/987


@wpoely86: looks pretty generic at first sight, yes, launchpad.net is used by DOLFIN, FFC, FIAT, Instant python-meep, UFC, UFL and Viper. Up for defining the constant, and fixing the `source_urls` in the relevant easyconfigs in a separate PR?