Fix transcript naming in mapping webservices

The following three webservice methods return a list of transcript
identifiers for some query:

- getTranscriptsRange
- getTranscripts
- getTranscriptsByGeneName

Previously they didn't work correctly for LRG transcripts (a bogus
version was included and no transcript was selected) and refseq
transcripts on mtDNA (no transcript was selected).

Additionally, the getTranscriptsRange method now optionally
includes version numbers with the boolean versions argument
(default false).