BUG: Add whitespace scrubbing from sample name

Sample names are now scrubbed for trailing white spaces.

Fixes #609
Merge branch 'master' of git://github.com/biocore/qiita into issue-609
TST: Fix tests to use assert_frame_equal
Merge pull request #616 from ElDeveloper/issue-609

BUG: Add whitespace scrubbing from sample name