#27: added feature to clean up old timeline data

[KoustavFrost]

Issue: #27

Changes:

• Added a background alarm task to clear timeline data automatically which are older than 60 days. This alarm job will run once a day.
• Also a button has been added under the settings section from where timeline data older than 60 days can be cleared.
• This will help clear the older data while keeping the newer timeline data.

[ritesh-cs]

Provide option to the user for number of days.

[ritesh-cs]

The textbox should show a default value of 60.
There should NOT be an arbitrary restriction of 7 days. User should be allowed to clear data beyond any value (even today)

Its possible to type in non numeric values.
This message is confusing. Please reword especially the italics part
No data available for (deletion beyond the 8 days timeframe).

The value in the textbox should not be cleared when the user hits the clear button.

Add something ,somewhere which says, the data will be cleared only from local cache and not from server (not the exact words but something similar)