Add button attribute to all add/remove button tags

The browser was activating add/remove buttons when the user pressed
enter.  Adding the type="button" to button tags prevents the user
from accidentally removing items from the multi-valued list.

HYDRASIR-535 #close
Merge pull request #543 from projecthydra-labs/feature/HYDRASIR-535

Add button attribute to all add/remove button tags
Set the file path correctly for predicate_mapping file
Merge pull request #544 from projecthydra-labs/feature/set-file-path-correctly

Set the file path correctly for predicate_mapping file
Merge remote-tracking branch 'upstream/develop' into fork-updates