Add assign-interviewers.html
Add .xls & .xlsx reading libraries
Add 'drop-target' directive to read dropped files
Create a template for 'assign-interviewers' option menu
Add incoming interviewers list check logic
Add 'add' and 'assign interviewers' API handling
Add css styles for 'assign interviewers' menu, recreate prefixed version, remove animation declaration from index.html, minor edits
Minor changes to 'assign-interviewers' template file
Add new requests for checking and assigning interviewes to angular NFIELD API factory
Add 'assign-interviewers' controller logic to SurveyListCtrl
Add 'quick overview' to README.md