Kaldi integration

The work in kaldi-integration branch consist of:
- Integrating UFAL-DSG/pykaldi Python wrapper to alex
- Scripts for building Kaldi acoustic models from forked Kaldi libraries in UFAL-DSG/pykaldi
- Scripts for building HCLG - dekoding graph in PublicTransportInfoCS domain
- Documentation

Reason for merge:
The core of the applications works. It does not break anything, just add new functionality.
The known bugs #37, #34 and also other bug-fixes can be solved in separate branches.