fixes #1310

updated documentation and tutorials to reference
validate_mapping_file.py instead of check_id_map.py.

also updated error messages to reference validate_mapping_file.py
instead of check_id_map.py
Merge pull request #1311 from teravest/issue1310

fixes #1310
can now detect and report script import errors
Add ScriptTester class

Still very preliminary, just starting the refactor. Seems to be working
Remove 'script_usage_output_to_remove' support

No longer necessary as we're not storing output in the repo anymore.
Add ScriptTester.result_summary
Refactor rest of code into __call__

Still needs cleanup and more testing, but appears to be (partially) functioning
Fix minor formatting issues
Add support for missing scripts
Finish implementation of script error handling

Also perform code clean-up and add docstrings/comments. Fixes #1304.
minor formatting fixes
removed extraneous line
i must be really tired...
Rewrite get_qiime_scripts_dir

Now runs the equivalent of 'which print_qiime_config.py' to infer the scripts directory.
update util.py modules, update some unit tests
update print_qiime_config.py and parallel scripts
update workflow library code
update denoiser code and add qiime.util.which

qiime.util.which is now my favorite python function
remove remaining refs to python_exe_fp
Update docs with config file changes