Made changes in libplot/CMakeLists.txt file so that the only necessary plplot-related variable that are necessary to set when building libblot is the PLPLOT_ROOT
Merge pull request #641 from chflo/ert_751_plplot_installation

Made changes in libplot/CMakeLists.txt file so that the only necessary p...
Changed the (duplicate) include_directories to be based on the appended CMAKE_INCLUDE_PATH, like the LIB thing
Merge pull request #642 from flikka/plplot_cmake_fix

Changed the (duplicate) include_directories to be based on the appended ...
ERT-782: Added exception class CWrapError
ERT-747: Created Python function to hook up abort() signals.
ERT-782: Added abort signals to ert_server.
ERT-782: Removed reference to missing __len__()
ERT-782: Added addSubstKeyword() function
ERT-782: Added some methods to job_queue manager
ERT-782: Added job_queue_manager to query one job
ERT-782: Made ert_socket multithreaded with mixin
ERT-782: Added method to get queue_index
ERT-782: Added name() method to enkf_node
ERT-782: Added load() method - and asserts on save
ERT-782: Server can restart simulation set:Locking
ERT-782: Can restart simulations sets. Locking
ERT-782: Server will loop on port occupied
ERT-782: Large changes to the ert_tcp_client:

  - The client has been renamed ert_tcp_test_client
  - The ability to run commands interactively has been removed, it can
    now only play through a json file.
  - A default hostname and port has been specified, but they can be
    changed with commandline argument --host=hostname:port
ERT-782: Added logging and argument parsing to ert_server