Make primer list available from within package

[thokall]

Instead of reading primers and metadata connected to this from excel file, we might move them to an internal object available form within the MetaBAnalysis package. This will make it easier to generate the table that is always in the report by creating a function that take the arguments:

1. Species group
2. Fragment
3. Temperature (no values should give standard settings here)
4. Etc

[thokall]

Change excel to .csv but retain the information in this file rather than including it in the package as it also can be used by cutadaptadapter.py and qc_generator.py

[thokall]

In addition to already available primer information we will also add info about, fragment size (anchored primer or not in cutadaptadapter.py and settings for dada2 analysis).