Adding ability to append to Tecplot ASCII files.

Adding a test for this capability.

This feature basically consists of writing multiple Tecplot ASCII
files into the same file using std::ofstream::app, which Tecplot is
indeed able to read.  The drawback is that the Mesh is written to the
file each time. I have a question in to Tecplot support to see if it
would be possible to have only one copy of the Mesh in the file,
similar to the way the Exodus file format works.

Appending is not currently supported for binary files, if you have
selected the binary output format for Tecplot, the ascii_append flag
will be ignored.  I'm also investigating appending to binary files, so
this interface may be updated in the future.

Refs #440.
add a special kernel for eigenvalue problems #2350
add the inverse power method and nonlinear eigenvalue executioner #2350
add two objects in test #2350
two tests for the eigenvalue executioners #2350
move some codes from EigenExecutionerBase to NonlinearSystem and other improvements #2350
Refactor EigenKernel
Adding multiple EigenKernels to the warehouse
TODO: Need to address proper execution
Implementing new EigenSystem
Ignore shared objects with suffixes on Linux
closes #2809
Updating libmesh.
Dummy commit.

Refs #000.
a new working version #2350
Merge commit '2cd1f8566869dbabbf00f1b74b9fe85c98e8625f'
Move tests from combined to solid_mechanics ref #2814
Few corrections #2350
a test showing how to use materials for the eigen executioners #2550
Merge pull request #2815 from bwspenc/move_tests

Move tests from combined to solid_mechanics
Invert inheritance order in Constraint-based contact classes ref #2816

The intermediate class SparsityBasedContactConstraint overwrites
computeJacobian to fill _connected_doc_indices.  Next step is
to split that code out into a separate method so that the other code
in computeJacobian isn't duplicated.
Create getConnecteDofIndices() method ref #2816

Move all the code that populates _connected_dof_indices into a
separate virtual method, and have the derived class just overwrite
that method rather than computeJacobian().
Merge pull request #2794 from jwpeterson/tecplot_append

Adding ability to append to Tecplot ASCII files.