Adding automation test script for control/fieldtype "Attach".

The above test script does the following testing:

1. Creating a new doctype with attach fieldtype.
2. Attaching a new image using the "Link" option from the options which the "Attach" button offers.
3. Checking if the URL of the attached image is getting displayed in the field of the newly created doctype.
4. Checking if the clicking on the "Clear" button clears the text in the field and again displays the "Attach" button.
5. Doing all the above testing by using the "Library" option from the options which the "Attach" button offers.