Observation app: bugs resolved in date picker and Image upload

**Errors in Observation app resolved:**
- Date-time-picker error is resolved.
  > *Where to check? : Just go for edit of any of the listed observation (LHS). Try to create/edit marker with add/edit of date and time.*

- File upload issue is solved.
  > *Where to check? : Go for adding the file to the marker. When edit view of the marker is visible, click on ```Attach File``` button. You could see overlay appearing asking to add file. Do it and click on ```Upload button```*