Refactoring for cgat-core

• update installation and conda environments ; #6
• migrate pipelines from ini to yml configuration files ; #11
• update conda from 4.3 to 4.5 (solving "CXXABI_1.3.9 not found" error ; ContinuumIO/anaconda-issues#5191) ; 122752d...e7f4a3a
• add exportdir when missing in pipeline.yml ; #14
• new way of activating conda environments ; #15