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