Merge branch 'issue564' of https://github.com/ebolyen/scikit-bio into issue-564
Merge branch 'master' into issue-564

Conflicts:
	skbio/alignment/_alignment.py
	skbio/tree/_tree.py
First working version of dm_to_DissimilarityMatrix
Refactor dm parser to support Dissimilarity/DistanceMatrix classes
Remove redundant DistanceMatrix tests
Refactor test code, much shorter/cleaner now
Make naming consistent in tests
Move docstring to module level

Docstring still needs to be updated.
Port dm writer code

Still needs unit tests.
Add dm writer tests
Port rountrip read/write test for dm format
Move writer code to keep ordering consistent with public functions
Merge branch 'master' into issue-564

Conflicts:
	skbio/alignment/_alignment.py
	skbio/io/__init__.py
	skbio/tree/_tree.py
Remove extra skbio.io import in top-level init
Add first (rough) dm sniffer implementation

Still need a lot of refactoring with parser and sniffer, more tests, and logic cleanup.
Push common file format test data into a base class
Improed sniffer delimiter detection
Add tests for sniffing CSV instead of TSV
Add tests to reader and writers for CSV
Add tests for header line without leading delimiter