made cheshire3.textmining PEP8 compliant
added NLTK-based part-of-speech normalizer
added textmining dependencies to setup.py
added unittesting for NLTK PoS normalizers
added to textmining README and made ReST

README for textmining sub-package made ReStructured Text
and made substantially more thorough
added docs for downloading NLTK data

Downloading NLTK data is necessary to ensure the presence of certain
trained models used by Cheshire3
Merge branch 'develop' into feature/nltk
fixed config for TsuPosNormalizer

taggerPath -> executablePath
fixed config for Enju Normalizer and PreParser

enjuPath -> executablePath + executable
fixed configs for Genia Normalizers

filePath -> executablePath
replaced commands.getoutput with getShellResult
fixed missing import of ConfigFileException
made textmining executablePath configs into templates
made enju executablePath configs into templates
made all textmining config objectTypes absolute
added configs for basic NLTK PoS taggers

* NLTKPosTagNormalizer
* NLTKJustPosTagNormalizer
added NamedEntityExtractor code and configs

Based on NLTK tokenizer, PoS tagger and named entity chunker.

Configs for:
- PersonNameExtractor
- PlaceNameExtractor
- OrganizationNameExtractor
- NamedEntityExtractor (all of the above)
added unittests for NamedEntityExtractors
added unittest for unsupported named entity type

Added unittest for NameEntityExtractor configured with an unsupported
entityType setting.
added unittests for variant NamedEntityExtractors

e.g. when configured with entityType setting: People, GEO,
companies etc.
etc.