DOC: Update docs to 2.0 and scipy 0.13.0

Fixes #383
DOC: Remove the concept of sparse/dense
DOC: Remove sparse/dense in biom_conversion.rst
DOC: Remov docs about the backends
DOC: Remove sparse/dense descriptions
DOC: Remove reference to table factory and types

Fixes #383
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DOC: Add mention of h5py to doc/index.rst

Thanks @wasade!
DOC: Add autoclass directive for Table class
DOC: Update required numpy version to 1.7.0
Add example for biom.table.Table exists method
Fix format of numpydoc parameters section

See section 4, "Parameters", of
https://github.com/numpy/numpy/blob/master/doc/HOWTO_DOCUMENT.rst.txt

When a parameter can only assume one of several values, put them in braces,
with the default first, and if the parameter is optional, indicate that.
Merge pull request #389 from ElBrogrammer/fork-me-brah

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Merge pull request #388 from ElDeveloper/issue-383

DOC/ENH: Update docs ⚠️ not ready for merge⚠️
Merge pull request #392 from adamrp/fix_table_numpydoc

Fix format of numpydoc parameters section
Merge pull request #391 from adamrp/table_exists_example

Add example for biom.table.Table exists method
API: added Table.pa
Merge pull request #395 from wasade/issue_125_pa

API: added Table.pa
Merge branch 'master' of github.com:biocore/biom-format into issue_125_sample

Conflicts:
	biom/table.py
	tests/test_table.py