Add task for Alpino dependency parser.

Task works by calling Alpino binary which is expected to exist in a folder
pointed to by ALPINO_HOME environment variable. This is not installed
automatically.

- _alpino.py contains logic for calling and interpreting Alpino
- test_alpino contains a simple test case to make sure it works

(It would be good to add some more tests, especially unicode related)

(fixed pep8 issues)
Added unicode test and fixed decoding and error messages
Alpino is for Dutch only + refactor task

output did not have a default value and was not validated.
This adds toolz to the dependencies, but I was going to use that
anyway.
Merge branch 'alpino'