Resolve spec inside and json_array and json_object

The object inside the $array or $object spec can now have values which can be sourced from the source object if the third boolean parameter boolean (contains_spec) is set to True

Pip Dependency Fix-ups

• Move PyPi requirements to requirements-dev.txt so that they cannot cause dependency conflicts.
• Remove python_requires version since the library is not dependant on features of a particular version of Python.

Initial release to PyPi

Merge pull request #3 from ebi-ait/more-pip-fixes

Pip dependency & python version fixes.

Fixed Package Name

• Rename package to json_converter
• Add installation & usage to readme
• Other Readme fixes