asset fix: don't allow THUMBNAIL_SEPARATOR in the asset filename.
asset fix: don't allow THUMBNAIL_SEPARATOR in the asset filename.

geoiq/digitalgazette,geoiq/digitalgazette,nilclass/echosocial,riseuplabs/crabgrass,ajturner/crisiscommons,adammck/crabgrass,adammck/crabgrass,riseuplabs/crabgrass,adammck/crabgrass,riseuplabs/crabgrass,ajturner/crisiscommons,riseuplabs/crabgrass,ajturner/crisiscommons,riseuplabs/crabgrass,riseuplabs/crabgrass,nilclass/echosocial,geoiq/digitalgazette,riseuplabs/crabgrass,ajturner/crisiscommons,nilclass/echosocial,adammck/crabgrass,nilclass/echosocial,geoiq/digitalgazette