New in ETA: Building matrices with a precomputed graph

This commits add support for precomputing matrix graphs
for building FE system matrices in a closed optimized form

Two new files: lifev/eta/expression/{BuildGraph,GraphElement}.hpp
handle precomputing the matrix graph

Changes in other files of ETA accomodate the new strategy and
selection of the open/closed path in an efficient manner.

Additions to the MatrixEpetra and MatrixEpetraStructuredView are
related to the usage of sumIntoGlobalValues, where appropriate,
without having an "if" clause in the FE loop.
Unit test for ETA graph precomputation

This commit adds a unit test to the ETA module that checks
the graph precomputation functionality and checks that
the matrices assembled with or without the precomputed graph
are correct.

Based on the first ETA tutorial
Reducing code duplication in IntegrateMatrixElement

The body of the FE loop in the IntegrateMatrixElement class
is moving to a new private integrateElement method which is
then used in the two version of the FE loop (for open or
closed matrices).

This is also a first step towards introducing a multi-threaded
FE loop to ETA
Removing unused data members from GraphElement.hpp
Performance improvement in GraphElement.hpp

Moving constructor of elemental matrix outside of the FE loop
Adding problem size and commandline param for eta test of static_graph
Making the graph lock procedure explicit
include source dir from top CMakeLists.txt
remove redundant include_directories for libraries
remove redundant include_directories for tests and examples
do not store LIFEV_HAS_* var in cmake cache
Adds the Navier-Stokes solver to LifeV
Adds new files + solve some problem in the compilations of the NS solver
Compilation fixgit status
Improving the compilation files
Adds some files required for the example of the NS solver
Merge branch 'master' into static_graph
Astyle for PrecomputedGraphETA branch
Offset support for ET assembly and graphs

This commit adds the support for specifying row and column offsets
when building FECrsGraphs or doing the FE assembly in with ET.

This functionality is needed for Stokes, Navier-Stokes problems
check for problems is already taken care by set -e