update to add methods to gnerate input phase and solvent XML.

phasecalculator/io/phasetransferxmlcreator.py

phasecalculator/test/iotest/phasetransferxmlcreatortest.py

phasecalculator/test/phasecalculatortests.py

phasecalculator/test/resources/expected_phase.xml

phasecalculator/test/resources/expected_solvent.xml