Get dependencies metadata from Dapi
HTTPS API calls

 * use HTTPS API URL as default
 * add aditional requirements for Python 2 to make requests work with SNI
 * modify install_requires in setup.py to respect that
 * while there, remove redundancy from requirements-devel.txt
 * update the developer documentation and README to reflect the changes
 * update Travis recipe to reflect the changes
Merge pull request #288 from hroncok/depmeta_and_https

Get dependencies metadata from Dapi + HTTPS API calls
Dapicli: Fix broken page argument and 404 handling
Ignore venv directory
Instead of the newgrp magic that doesnt work with docker-py, just tell user to log out and in again.
Make sure exit functions are run if DA is killed by SIGINT
Make sure not to fail on missing 'time' key in _docker_stop
Implement modifying environment variables, fixes #289
Fix encoding problems in GUI logs, fixes #290
Some documentation TODOs, fixes and tweaks
2FA, Refactored logging into GitHub (fixes #244)
Change the pingpong title to be more descriptive to people who don't know what pingpong is :)
Allow one top-level snippet
Merge pull request #291 from hroncok/docs_dap_snippet

Allow one top-level snippet in the docs
Move installed meta.yamls to meta dir
Merge pull request #292 from hroncok/metamove

Move installed meta.yamls to meta dir
First attempt at vagrant support for running/building docker containers and images
Make for loop work with lists properly
More improvements to docker command runner:
- DA now depends on docker-py
- old methods invoking commandline are now removed
- proper checks of arguments passed to docker-py