Add concat filter to fix issue with jquery-pjax
Add concat filter to fix issue with jquery-pjax

jquery-pjax makes use of IIFEs but does not terminate its last statement with a
semicolon, causing syntax errors after asset concatenation. See also:
https://github.com/miracle2k/webassets/issues/100#issuecomment-388461033

cburmeister/flask-bones,cburmeister/flask-bones,cburmeister/flask-bones