GBS pili and surface protein typing

Added options to perform GBS pili and surface protein typing.
Downgraded Blast version of docker image due to headers incompatibility.
Added sequence length information in assembly mode.
Added possibility to write new alleles found.
Removed the culling limit during Blast search.
Added the possibility to change the number of reads mapping locations in reads mode.
Several bug fixes.

Assemblies

Allow typing from fasta files using Blast
Create specific module for E. coli stx subtyping
Create a script to update STX sequences from virulencefinder_db
Add Dengue virus serotyping/genotyping reference sequences
Update README
Minor fixes