Fixed order-dependent tests.

Fixes #123.
Added include_collapsed_metadata argument.

Added optional argument include_collapsed_metadata=True to Table.collapseSamplesByMetadata and Table.collapseObservationsByMetadata.
Added observation_column_name argument.

Table.delimitedSelf now has an optional argument, observation_column_name, which allows the user to specify the name of the first column in the output table.
Added Table.transpose method.
Added optional argument constructor.

Added optional argument, constructor, to Table.bin*ByMetadata and Table.collapse*ByMetadata.
Made filtering error messages a little clearer.
Add one_to_many_mode to Table.collapse*ByMetadata.
Merge pull request #150 from jrrideout/one-to-many

Several misc. changes necessary for QIIME issue #998