Squash-merges PR #571 (rebased from contributor PR #566 by @renheqiang). Adds .xls/.xlsx/.doc/.docx to the file picker and MIME map. 1319 tests pass.
Squash-merges PR #571 (rebased from contributor PR #566 by @renheqiang). Adds .xls/.xlsx/.doc/.docx to the file picker and MIME map. 1319 tests pass.