[3.4] Fix a non bootstrap dropdown

bevor patch
![bevor_dropdown_issue](https://cloud.githubusercontent.com/assets/2596554/4431641/530c493c-4671-11e4-8a25-04707308db2f.JPG)

after patch
![after_patch](https://cloud.githubusercontent.com/assets/2596554/4431643/5a66419c-4671-11e4-9c75-eda09b901ad3.JPG)

See here: BE --> Extensions --> Template Manager --> Isis --> Advanced