Allow using barnaba command line from python

[GiovanniBussi]

This is an iteration of #28. I think I fixed the last issue so that it could be merged.

The goal of this change is to allow users to do the following

import barnaba.commandline
barnaba.commandline.main(["ENM","--pdb","test.pdb")

This would allow using from python the features that are implemented in the command line interface. It will thus allow to add nosetests for the command line interface. Most importantly, using command line tools from python allows to speedup the processing of multiple files (bin/barnaba is very slow at startup due to mdtraj import).

Changes are pretty small, and are better seen looking at the individual commits:

• de0dc868d7e4c27534b04a67200ebc6a86703d2f I made the command line interface callable from python
• 8a153dbcf57d82ae8c1a0379236fea0a21db9b4b move /bin/barnaba to barnaba/commandline.py. This makes the command line available from python
• a9605e674d7a0c5b22b9715c7626807b3edc8ed9 restore the bin/barnaba script, now just calling barnaba.commandline.main()
• a7fa54afd0b76314e7c0f33f71f40755c7ac6610 makes it possible to call main with a string barnaba.commandline.main(["ENM --pdb test.pdb")
• fca8f4071c8102a496448173971be0784470e344 adds a regtest for ENM command line.

[codecov-io]

Codecov Report

Merging #39 into master will decrease coverage by 11.22%. The diff coverage is 24.75%.

@@            Coverage Diff            @@
##           master    #39       +/-   ##
=========================================
- Coverage   67.22%    56%   -11.23%     
=========================================
  Files          13     14        +1     
  Lines        1968   2675      +707     
=========================================
+ Hits         1323   1498      +175     
- Misses        645   1177      +532

Impacted Files	Coverage Δ
barnaba/commandline.py	24.75% <24.75%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 66fbb82...fca8f40. Read the comment docs.