ERT-699: Added contains method to the vector template
ERT-699: Added list of report_steps to gen_data_config
ERT-699: Removed unused variable.
ERT-699: Added flag dynamic to gen_data_config_alloc()
ERT-699: gen_data_config refactoring + testing I

Have refactored the functionality to create and initialize the
gen_data_config nodes.
ERT-699: gen_data_config refactoring + testing II
ERT-699: gen_data_config refactoring + testing III
ERT-699: gen_data_config refactoring + testing IV

Have added the REPORT_STEPS:xxx attribute as required for the GEN_DATA
configuration.
ERT-699: Updated enkf_config_node->internalize vector
ERT-699: Renamed __load_state -> __load_eclipse_restart
ERT-699: Fixed GEN_PARAM -> GEN_DATA
ERT-699: Removed call to ensemble_clear_internalization()

As part of the function enkf_main_init_run() the function
ensemble_config_init_internalization() was called to clear the
internalization flag of all the nodes. This had the uninted consequence
of clearing the internalization flag of the gen_data nodes, thereby
loosing the REPORT_STEPS: config which has been loaded from the
configuration file.
ERT-699: gen_data_forward_load() can return false.

Due to the weak ordering of the GEN_DATA data containers the
gen_data_forward_load() function previously returned true
unconditionally; if no result file was found that was interpreted as
size 0. If the missing file was indeed an error that would subsequently
lead to a hard crash due to size mismatch in
gen_data_config_assert_size( ).

With this commit the gen_data_forward_load() will return false;
i.e. indicate load failure if no result file is found.
ERT-699: Added very basic EclSum::writer()
ERT-699: Added obs_vector check that gen_data is active
ERT-699: Log message about gen_data loading -> stderr
Merge pull request #555 from joakim-hove/ERT-699-gen-data-with-report-steps

Added REPORT_STEPS: to the GEN_DATA configuration