KEGGAPI: raise to 8 the number of retries
In some cases it may worth to wait a bit longer and retry before a failure
For instance, in CentOS, after a while that we query the KEGGAPI we start to
get some errors.
KEGGAPI: avoid multiple requests at the exact same time on failures
KEGG: avoid failures when fetchKegg works correctly
dphenome: get the activity distribution by plate_id
KeggAPI: new option to never fail during kegg data fetch