Fix all_test.py failing with ImportError ( #215 )

Given that some functionality from qiime.test was moved to qcli.test,
this import was failing in QIIME-1.7.0-dev, this has been resolved and
supports both 1.7.0 and 1.7.0-dev.

Fixes #215
Merge pull request #217 from ElDeveloper/issue_215

Fix all_test.py failing with ImportError ( #215 )