Partially solved Warning/nan in Exercise 2.9

These are caused by the log-domai operations, which lead to not-a-numbers (nans) in posterior decoding. The recognition rates reported are thus not correct. This has been solved by changing the logzero() to -1e20 and using safe_log() to treat the case log(0) separately.

The performance of posterior decoding is now much higher. I get

Test Set Accuracy: Posterior Decode 0.862, Viterbi Decode: 0.867
Merge branch 'master' of https://github.com/ramon-astudillo/lxmls-toolkit
Merge branch 'master' of https://github.com/gracaninja/lxmls-toolkit
Undid the log-domain changes in lxmls-toolkit/labs

Since this folder is already asynchronous with lxmls-toolkit/lxmls/labs there is no much sense in working here at the moment
Merge remote branch 'upstream/master'
Updated test script for day5

Deleted old command line calls that were not used in the current exercise setup. Added information regarding amazon experiments and made sure all paths exist.
Changed day5 last exercise to smaller datasets

As it was indicated in the guide. I had left the original ones which are much bigger.
Merge branch 'master' of https://github.com/gracaninja/lxmls-toolkit

Conflicts:
	lxmls/labs/day5.sh

kept comments on last exercise on amazon
Merge remote-tracking branch 'upstream/master'
Merge remote-tracking branch 'upstream/master'
This branch now contains the LxMLS labs version

Removed parts of the code that have to be completed byt students.

Removed instaler as this is not intended to be used.
README adapted to labs branch, pip-reqs reduced

Removed configparser==3.2.0r3 from pip-requirements.txt
Added solve.py script that solves exercises

call as e.g. python solve.py day2
Merge pull request #26 from ramon-astudillo/student

First version of future student branch