Display id instead of accession number in the sequence modal.

This works correctly only on BLAST 2.2.30+. Older BLAST+ will include 'lcl|' in
the id for non nr and blast databases which is unwanted. We could have stripped
'lcl|'. Instead we will change minimum BLAST+ version requirement (because we
anyway need at least 2.2.29+ for sequence retrieval to be robust).

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>
Refactor, document and clean up Sequence class.

Signed-off-by: Anurag Priyam <anurag08priyam@gmail.com>