Create reporter importer for GTF files

[Nicklas Nordborg]

A description of the GTF file format can be found at: ​http://www.ensembl.org/info/website/upload/gff.html

The importer should use either the "gene_id" or "transcript_id" as the reporter id and also have an option to use a prefix (eg. hg19).

Other reporter annotations should be configurable to use either one of the standard columns or one of the attributes.

We should provide a default configuration using a standard setup.

This is related to #1153.

[Nicklas Nordborg]

(In [5761]) References #1623: Create reporter importer for GTF files

Column mapping expressions was incorrect. Should be <gene_id> / <transcript_id>.

[Nicklas Nordborg]

(In [5759]) Fixes #1623: Create reporter importer for GTF files

[Nicklas Nordborg]

(In [5770]) References #1623: Create reporter importer for GTF files

The default configuration now uses transcript_id@seqname as the reporter id. We discovered that this is needed to make up a unique id for all entries that we want to track in array design features and raw data.