Utilize sample tsv for single sample

[LeeBergstrand]

• Get single sample information from the sample.tsv file rather than the config.
• Slight bug fix to rotary.py

[LeeBergstrand]

@jmtsuji I made new code that addresses some of your comments, and https://github.com/jmtsuji/rotary/issues/53

• added a flag to creating sample objects that skips the integrity checks.
• skips integrity checks in run_one and when parsing existing sample tsvs.
• adds a function that parses the sample.tsv into the dictionary of sample objects keyed by sample identifier.
• rotary.smk now uses these objects.