updated so script usage test output from all_tests.py is more informative

Fixes #950.

Not 100% sure we want this, as it requires me to move a function (now ``qiime.test.run_script_usage_tests``) from qcli 0.1.0. I don't think this is really a bad thing since QIIME is likely the only software using ``run_script_usage_tests`` currently, and QIIME will be ported to use pyqi instead of qcli, so ``run_script_usage_tests`` is likely going to only be in QIIME for one release cycle. 

@jrrideout, what do you think? Do we want this?

If we go with this, the new script usage test failure output will look like the following (note that one of the ``align_seqs.py`` scripts is failing):

```
$ python tests/all_tests.py --suppress_unit_tests --script_usage_tests align_seqs,make_otu_table,summarize_taxa
Tests to run:
 align_seqs make_otu_table summarize_taxa

Testing 4 usage examples from: /Users/caporaso/code/Qiime/scripts/align_seqs.py
Running tests in: /Users/caporaso/temp/script_usage_tests/align_seqs
Tests:
/Users/caporaso/code/Qiime/scripts/align_seqs.py -i $PWD/unaligned.fna -t $PWD/core_set_aligned.fasta.imputed -o $PWD/pynast_aligned_defaults/ : Pass
/Users/caporaso/code/Qiime/scripts/align_seqs.py -i $PWD/unaligned.fna -t core_set_aligned.fasta.imputed -o $PWD/pynast_aligned/ -e 500 -p 95.0 : Pass
/Users/caporaso/code/Qiime/scripts/align_seqs.py -i $PWD/unaligned.fna -m muscle -o $PWD/muscle_alignment/ : Pass
/Users/caporaso/code/Qiime/scripts/align_seqs.py -m infernal -i $PWD/unaligned.fna -t $PWD/seed.16s.reference_model.sto -o $PWD/infernal_aligned/ : Failed
Stdout:
Stderr: Traceback (most recent call last):
  File "/Users/caporaso/code/Qiime/scripts/align_seqs.py", line 205, in <module>
    main()
  File "/Users/caporaso/code/Qiime/scripts/align_seqs.py", line 188, in main
    log_path=log_path,failure_path=failure_path)
  File "/Users/caporaso/.virtualenvs/qiime/lib/python2.7/site-packages/qiime/align_seqs.py", line 182, in __call__
    cmbuild_params=cmbuild_params)
  File "/Users/caporaso/.virtualenvs/qiime/lib/python2.7/site-packages/cogent/app/infernal.py", line 1347, in cmalign_from_alignment
    refine=refine,return_alignment=True,params=cmbuild_params)
  File "/Users/caporaso/.virtualenvs/qiime/lib/python2.7/site-packages/cogent/app/infernal.py", line 1259, in cmbuild_from_alignment
    params=params)
  File "/Users/caporaso/.virtualenvs/qiime/lib/python2.7/site-packages/cogent/app/util.py", line 165, in __init__
    self._error_on_missing_application(params)
  File "/Users/caporaso/.virtualenvs/qiime/lib/python2.7/site-packages/cogent/app/util.py", line 434, in _error_on_missing_application
    % command
cogent.app.util.ApplicationNotFoundError: Cannot find cmbuild. Is it installed? Is it in your path?




Testing 3 usage examples from: /Users/caporaso/code/Qiime/scripts/make_otu_table.py
Running tests in: /Users/caporaso/temp/script_usage_tests/make_otu_table
Tests:
/Users/caporaso/code/Qiime/scripts/make_otu_table.py -i otu_map.txt -t tax_assignments.txt -o otu_table.biom : Pass
/Users/caporaso/code/Qiime/scripts/make_otu_table.py -i otu_map.txt -o otu_table_no_pynast_failures.biom -e pynast_failures.fna : Pass
/Users/caporaso/code/Qiime/scripts/make_otu_table.py -i otu_map.txt -o otu_table_non_chimeric.biom -e chimeric_seqs.txt : Pass


Testing 2 usage examples from: /Users/caporaso/code/Qiime/scripts/summarize_taxa.py
Running tests in: /Users/caporaso/temp/script_usage_tests/summarize_taxa
Tests:
/Users/caporaso/code/Qiime/scripts/summarize_taxa.py -i otu_table.biom -o ./tax : Pass
/Users/caporaso/code/Qiime/scripts/summarize_taxa.py -i otu_table.biom -o tax_mapping/ -m Fasting_Map.txt : Pass

==============
Result summary
==============

Script usage test result summary
------------------------------------

Ran 9 commands to test 3 scripts. 1 of these commands failed.
Failed scripts were: align_seqs.py
```