Added unit test for to_fasta

The commit adds unit testing for checking the behavior of to_fasta
method : that is add fasta header if sequence header is absent otherwise
return the sequence.

Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>
Added unit test for uniquification of sequence ids

Appropriate unit tests are added to ensure unique sequence ids for
multiple sequence queries..

Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>
Removed unused variable and typing mistake

Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>
Eliminate sequence name collisions

This patch ensures that all blast queries have unique indentifier ids.

Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>