Removed common code for listing cards of diff types in each tab to generic template file_list_tab.html

**Changes in ```file.html``` which is used to show files list-view/card-view:**
- We were having redundant code to generate card for each *mime_type*/tab.
- Which is moved to ```file_list_tab.html``` generic template.
- Included generic template wherever required with include-specific/distinct variable values.
- Now further on when we need to add new tab(mime_type), just need to include template with variable values.
- Also now code is well indented.