Refactored code for stock data import

* Logic not in command
* Simple tests for strain & plasmid importer
* Use of Test::CSV for data file parsing
* `croak` in proper places
* `nextval` for sequential concurrent uniquename generation for PostgreSQL

*Note:*
* Commits starts from
**Sept 18, 2013 - Redesigned strain importer**
* Commits before that are due to improper branching !
* Will have merge-conflicts. Will be resolved manually !