Merge branch 'fix_issue_685' of https://github.com/antgonza/qiime into fix_issue_685
updated to use open-reference otu picking and core_diversity_analyses.py

need to make an udpate to qiime to use change from #741.
updated to use open reference otu picking and core_diversity_analyses.py
added check_id_map.py step
Fixing --input_fps option for count_seqs.py. Not finished (currently does not support filepath pattern expansions)
Added estimate_observation_richness.py module.

Also added corresponding test module with the start of an implementation (and tests) of AbstractObservationRichnessEstimator.
Added some utility methods needed by estimators.
Added check for empty biom table.
Added abundance frequency counts calculation.

Also added check for empty samples.
Added chao1 full richness estimate calculation.
Added __call__, which raises NotImplementedError.
Added ObservationRichnessInterpolator class.

Can currently interpolate based on a number of points and the Chao1 full richness estimate. Does not calculate variance yet.
Added equation reference.
Refactored full richness estimate functionality.

Now fits the Strategy design pattern, as we're going to at least add ACE (in addition to Chao1).
Fixed bug when point_count == 1.
Refactored interpolator estimate code.

In preparation for adding variance calculation.
Added variance calculation for interpolator.
Added comments indicating test result verification
Added more tests for Chao1 calculation.
Refactored to have two families of algorithms.

There are now PointEstimators and FullRichnessEstimators, which are used by ObservationRichnessEstimator.