Removed future from __init__

Since __init__ is imported by setup.py, future may not be installed yet.

Other options would be:

* Read VERSION -> and that code has to be duplicated in setup.py and
  senpy (to avoid the import, once again)
* Eval version.py
* Do without versioning :)

senpy/__init__.py

@@ -17,9 +17,6 @@
 """
 Sentiment analysis server in Python
 """
-from future import standard_library
-standard_library.install_aliases()
-
 from .version import __version__
 
 import logging

senpy/extensions.py

@@ -2,6 +2,8 @@
 Main class for Senpy.
 It orchestrates plugin (de)activation and analysis.
 """
+from future import standard_library
+standard_library.install_aliases()
 
 from .plugins import SentimentPlugin, SenpyPlugin
 from .models import Error, Entry, Results