Add aug_data method to augment existing PDB data and features

[CunliangGeng]

Added aug_data method to augment existing PDB data and features for all non-augmented molecules from a HDF5 file. Users can use it to create augmented molecules or add more augmentations.

[coveralls]

Pull Request Test Coverage Report for Build 806

• 47 of 52 (90.38%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.3%) to 76.941%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
deeprank/generate/DataGenerator.py	47	52	90.38%

Totals
Change from base Build 801:	0.3%
Covered Lines:	1615
Relevant Lines:	2099

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💛 - Coveralls

[NicoRenaud]

sorry for the delay I forgot that one !
But it looks good to me