Updates to Tecplot Outputter:

* Tecplot Outputter now writes binary files with .plt extension, ASCII
  files with .dat.  ASCII .dat files are written by default and don't
  require libmesh to be configured with --enable-tecplot to do so.

* Adding a test of binary tecplot ouput. This test requires libmesh to
  be built with --enable-tecplot to work properly.

* Updating test harness to check for libmesh's Tecplot API configuration status.

Refs #440.