Initial commmit of xvg2hdf from mercurial repo.

Migrating the xvg to hdf5 converter from the original mercurial repo to the new
github repo.
Add test Polaris *.xvg output file.

Generated a test Polaris output file that contains the header information of
the calculation, and the result of two snapshot calculations. Note that the
first two snapshots are still within the burn-in period of the simulation, and
are therefore physically unrealistic. This test file is simply used to test
file parsing/conversion programs to ensure that they conform to official
Polaris output.
Update module imports and comments.

Removed bulk module imports and updated comments to reflect HDF5 use instead of
*.xyz file use.
Merge branch 'hdf5-prototyping' into develop