Remove check for file before write

Fixes #274.
ENH: Add with and without H5PY tests in travis.yml

DO NOT MERGE.

Fixes #288
Change function call to "to_json"
MAINT: removing unused methods
ENH: passing shape now to dict_to_sparse
MAINT: removing unused imports
ENH: Remove h5py on USE_H5PY=False
API: summarize-table no longer can do md5
STY: line to long
ENH: Uninstall h5py after pip installs it
ENH: Uninstall h5py using pip instead of conda
STY: Group together the conditional statements.
poop
Merge pull request #374 from wasade/issue_272

Issue 272
Merge pull request #375 from wasade/issue_366

Issue 366
Merge pull request #372 from ElDeveloper/issue-288

ENH: Add with and without H5PY tests in travis.yml
Merge pull request #370 from adamrp/issue-274

Remove check for file before write
added tests and numpy docstring
Merge branch 'master' of https://github.com/biocore/biom-format into issue289