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'
friendlier output from clustering algorithms

Fixes #29.
install tests
forgot six requirement
suggest apt-get installation of six
refactor: use toolz instead of own batches helper
Added wrapper for the CoreNLP lemmatizer and parser.

CoreNLP is called using subprocess.Popen and kept in memory.
refactor/validate output arg in CoreNLP wrapper
run Stanford NER via pipes, not sockets

Committed the .class file to prevent a dependency on JDK.
Java wrapper code is licensed under the GPL because it has to link to
Stanford NER.
clarify documentation for Stanford NER task
simplify tokenizer; no longer return dicts
add simple /run/ REST endpoint
2.99.7
add missing tasks to API docs
docstring for /run/ in webserver
document REST API and prettify its results a bit

Fixes #61
Add semafor

- Added semafor semantic tagger
- Added task in xtas.tasks.single
- Added test cases for semafor