ERT-651 Minor fs read check fixup
ERT-651 Added python tests for GenDataConfig, to test the active_mask when swapping cases. Updated active_list representation to be valid also when no _active file exists on disk.
ERT-651 Added enkf_fs_type as argument to enkf_node implementations, need this in gen_data to read/write the correct active_mask representation.
ERT-651 ASCII art upgrade
ERT-651 Adds enkf_fs instance to observation nodes, to be able to find active mask for gen_obs dynamically.
Added test to CMakeList, removed some debug printing.
Added test with modification of active_mask, to check that the data gets reloaded
ERT-651: Removed author: from __init__.py
Merge pull request #526 from flikka/ERT-651-active_list

Ert 651 Make sure the active_list is always valid