Support POST examples and output.

Improved the documentation on the POST requests. Currently supports Perl
and the JavaScript examples. Need to expand to other languages before
it's ready.
Now use an example as the message format and expand examples.

We now have post examples in all the languages/applications we support.
There are also improvements to the way we handle to post format by
reusing the existing examples rather than forcing the user to define a
fresh set of duplicate values.
Merge pull request #29 from willmclaren/master

Add vep/hgvs endpoint
Merge pull request #31 from Ensembl/experimental/betterpostdoc

Experimental/betterpostdoc
missing slash in path
missing initial / in url
missing example config for lookup post endpoint
better error catching for HGVS
added hgvs examples for production configuration
REST version for release 78 updated
new feature types available
Vep renamed to VEP
need to explicitly remove Vep file
ENSCORESW-1139: remove html=1 to let the correct controllers set the format
ENSCORESW-1139: now that html is not set on by default, set it to default if it was not already done by the controller
update docs pointer to latest version
ENSCORESW-1129: moved BED serializing logic to core directory, in Utils/IO
cache VariationFeatures before fetching TranscriptVariations so we don't have to do one DB fetch per TV