Travis updates

Check for selection of transcript in pos converter

Position Converter should error when no gene or transcript is specified
on accession numbers where this is required.

Fixes #190

Links in standalone mode should retain this mode

Fixes #287

Update dependencies

Mutalyzer used the `reverse_complement` function from the description
extractor, which was a unicode string-only implementation.

With this update, that implementation was removed and the BioPython
reverse complement function used instead in the description
extractor. Unfortunately this cannot work with unicode strings, so we
now use our own `reverse_complement` which works on unicode strings.

Minor clarification in release docs

Release 2.0.16

Only run import-reference on mitochondrial refs

Refactor transcript reference construction

LRG transcript mappings

Previously the getTranscriptsMapping webservice method didn't return
enough information to construct a complete transcript name. This is now
reported in a new `transcript` field.

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).

Note that we explicitely only support LRG references as transcripts,
so using c. positioning to convert to/from chromosomal positioning.

Supporting LRG references as genomic referenes, so using g. positioning
can be future work but converting them to/from LRG transcripts is of
course already done by the name checker.

Converting between genomic LRG positioning and chromosomal positioning
directly is not something that can be easily supported in the current
setup of the position converter.

Improve error message when reference is too large

This will mainly help when the user tries to use a chromosomal NC
reference in the name checker.

Set process name for long-running processes

For long-running processes it can be convenient to have a short and
human-readable process name. For example, in our typical server
configuration we have quite a few Mutalyzer processes running with very
long process names, making ps and top output hard to parse.

It is assumed that in production environments the webservices and
website are ran in a separate WSGI server such as Gunicorn which can be
configured to set the process name.

The setproctitle dependency for this feature is a C extension and we
therefore make it a soft dependency. Construction copied from Gunicorn:

https://github.com/benoitc/gunicorn/blob/5bc13be79ecaf8f1027764c600023f674ebcf5b2/gunicorn/util.py#L55

Don't report ext*? when variant RNA has stop codon

With the change introduced by #65 we forgot if the variant RNA has an
alternative downstream stop codon and therefore always reported ext*?
when the original stop codon was removed.

Fixes #145

Release 2.0.15

Degrade gracefully on HTTP error from Entrez

Add gene feature to genbank file without version