Add `genome disk allocation purge` CLI

It requires a `reason` and a list of `Genome::Disk::Allocation` objects.
clarify help_detail to roughly describe purging
use sprintf style status messages
differentiate help for Purge and Deallocate
remove duplicate fasta entries and add test
rename module to FilterSequences
die if fasta entry id is duplicate but sequence is different
Use the term FASRA consistently
store existing sequence in a variable
Updated class browser cache.
Updated `genome` tab completion.
Merge pull request #337 from susannasiebert/epitope_prediction

Remove duplicate sequences from fasta file
Merge pull request #331 from mark-burnett/add-purge-command

Add `genome disk allocation purge` CLI