Adding additional flags/arguments when assembly algorithms are called

[danejo3]

As we continue to explore and find the best flags/parameters for any given assembly algorithm (#2 ), we'll need to add these flags/parameters when they are called.

In #16 , a config file was introduced to YEAT. In this file, each JSON entry will contain the assembly algorithm's name and extra_args.

Currently, YEAT calls each assembly algorithm with hardly any additional flags. Depending on how we go about #15 , this may influence the way we handle the extra_args entry from the user's config file.