Agamemnon

* Adds the ability to set default_consistency_level for operations in Cassandra clusters.

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* Added many tests and fixed bugs with certain operations

* Added RDF support through RDFlib

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* fixed bug with in memory column comparisons

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* fixing bug with root reference node, adding support for unicode serialization and bumping version num

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* adding method to get all relationships regardless of type

* removing generated doc files and updating index.rst

* adding doctest to usage documentation and setup.cfg

* updating setup files with requirements

* multiple fixes for issues discovered by globusonline

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* added support for contains operator (with relationships_with(other_node_key) function) and added type conversion for pr

* merging relationship code from globusonline