Handling for docx, pdf, xls, xlsx

Added text-extraction capability for docx, pdf, xls, and xlsx files.
Added error handling to fileTextExtractor.py

Added try / except blocks to code.
Handle multiple excel sheets in a workbook

Code will now iterate over all Excel worksheets instead of just sheet 0.
Handle integer values in Excel

Excel values are returned as floats, even when they're entered as
integers.  These are converted back to integers on our side now.
changed app.yaml to resolve conflict