Fixed: order of operations in workflow.py which corrects offset abstractions

Previously the notes and intervals indexers were called together before
run_off_rep() and the ngram indexer. Now the order is notes, run_off_rep,
intervals, ngram indexer, and the rest is unchanged. The purpose of this is
to correct the calculation of horizontal intervals in n-grams when filtering
by offset. The fix works but the tests still need to be rewritten to
accomodate these changes.

Related to #310
Docs: added explanation of when the continuer will not get activated

By putting the interval indexer after the offset filter, the continuer
will not get activated when one may have expected it to. To clarify this
I added notes to the documentation in the settings and the
`FilterByOffsetIndexer` portions of workflow.py

Related to #310
Tests: integration test on workflow.py now correspond to new workflow

Putting the interval indexer after the offset indexer in the workflow
causes the continuer to no get used when pieces are filtered by offset.
This corrects the integration tests of the continuer settings by running
analyses without filtering by offset. Three csv files of expected
results are added. Now the Kyrie_short.krn piece in the test corpus is
unused but it is being left in because it may be used later.

Related to #310
Merge branch 'master' into new_workflow_order
Fixed: Unicode String Literals --> String Literals

We'll prepare for python 3, now that music21 made the leap!
Formatting: Refactor WorkflowManager._two_part_modules()

After Alex's revisions, I realized there are a couple of other things we
could smooth over. So, before rewriting the unit tests, I did it.
Fixed: Revise Unit Test for WorkflowManager._two_part_modules()

Accounts for part of the changes in a787a568201601216c8510855de503739d13f1f6

Working toward issue #310
Formatting: Minor Cleanup as Suggested by Pylint
Merge branch 'master' into new_workflow_order
Merge branch 'master' into new_workflow_order
Tes: New test to NGramIndexer

Refer to issue #261
Refactor: Swap order of parameters in AggregatedExperiments.get_data()

Previously, you specified aggregated then independent analyzers; now it's
independent then aggregated analyzers. This reflects the order in which the
analyzers will be run.

Also changed the only place WorkflowManager uses an AggregatedPieces.

Closes #326
Style: Cleanup for AggregatedPieces

In the tests, there was some really icky stuff, but now it's a little better.

In the class, I removed the failure-inducing overrides of __str__(), __repr__(),
and __unicode__().
Refactor: WorkflowManager.export ==> _export()

All output methods are now consolidated in WorkflowManager.output().

Closes #317
Merge branch 'new_workflow_order' into devel_2

This took a good deal of work, as merges go. But now we have the revised
workflow order for VIS 2!

Conflicts:
	vis/tests/test_workflow_experiments.py
	vis/tests/test_workflow_integration.py
	vis/workflow.py
Tests: Refactor the integration tests for VIS 2.

Tests 7, 8, and 9 are all wrong. Because I'm 100% sure that expected results for
tests 7 and 8 are correct, because I double-checked them by hand just now, this
means I'm really not so pleased.