axonomy default value

add support for taxonomy default value when options is set
Extension limitation with fileupload

Attempt to establish a test on the fileupload (js) to allow only certain
file type.
Using the keyword "extensions" word in the declaration of the fields in
contenttypes.yml
Bolt.js text corrections

semantic translation errors
PSR-2 Correction

Tabs to spaces conversions
Merge branch 'master' of github.com:odlex/bolt into odlex-master

Conflicts:
	app/src/Bolt/Content.php
Merge branch 'master' of https://github.com/bolt/bolt