Now all branches will be tested by Travis.

This enables testing on developer repositories.
Removed email notification.
Merge pull request #464 from endJunction/SetMinimumGCCVersion481

Require minimum gcc version to be 4.8.1.
Merge pull request #469 from bilke/travis-all-branches

Now all branches will be tested by Travis.
[A] Improve #include order.
[A] Remove wrong error message when no mesh present.
[PL] Correct messages for process variables.
[PL] Add mesh subset to initialize().
[PL] Initialize MeshSubsets and MeshComponentMap.
[PL] Rename mesh_items_all_nodes; items->subset.
[PL] Add destructor for GroundwaterFlowProcess.
[PL] Move mesh_component_map to class variables.

...from the initialize().
Also delete it in the dtor.
[PL] Add createDofMap() in Process.
[PL] Use number of node's DOF in createDOFMap().
[PL] Remove MeshComponentMap include from GW.
[PL] Add dof_map to GroundwaterFlow.
[PL] Empty solve().
[PL] Add empty GroundWaterflowFEM.
Merge branch 'SkeletonProjectData' into develop
Merge branch 'GroundwaterFlow' into develop