Reflected the API change in risklib
Merge pull request #6 from gem/fix-vf-converter

Reflected the API change in risklib
Moved modules to manage sources and logic trees from the engine
Moved utils/general.py from the engine
working for package
Merge branch 'pro-pkg' into source-and-logictree
add hazardlib as deps and fix descriptions
packager.sh: deps_list function bugfix
PYTHONPATH updated with hazardlib too
Fixed an import
Merged heads
Merge pull request #7 from gem/source-and-logictree

Moved modules to manage sources and logic trees from the engine
Removed logictree.enumerate_paths
Introduced a GsimLogicTree class
Fixed the random seed
Improvements to GsimLogicTree
Simplified the GsimLogicTree API
Turned logic tree instances into iterable yielding realizations
Improved docstring and comments
Some renaming to make the logic tree management more general