Got rid of biotypes.py

[iskandr]

Biotypes are now just strings whose validity is no longer checked. Trying to keep up with additions to the set of Ensembl biotypes was a nightmare.

Other changes:

• Changed Transcript.id -> Transcript.transcript_id, Transcript.name -> Transcript.transcript_name and made equivalent changes for Gene. For backward compatibility added id and name properties to Gene and Transcript.
• Added biotype as an argument to LocusWithGenome.
• Added is_protein_coding property to LocusWithGenome.

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This change is

[iskandr]

Closes #155

[coveralls]

Coverage decreased (-0.1%) to 81.392% when pulling 46b5cb2 on goodbye-biotype-checking into 6fbf8ad on master.

[coveralls]

Coverage decreased (-0.1%) to 81.392% when pulling 46b5cb2 on goodbye-biotype-checking into 6fbf8ad on master.

[coveralls]

Coverage decreased (-0.1%) to 81.392% when pulling 87fa186 on goodbye-biotype-checking into 6fbf8ad on master.

[iskandr]

@timodonnell called this "astoundingly amazing" and "excellent".