some interactions omitted in steps 9, 13, 18 of ISO test Install (auto-resize)

[Premek Brada]

After going through 15.04 ISO install testing, I suggest the following could be updated in the test case "Install (auto-resize)":

* step 6 should read Click on _Continue_

* step 8 should read Move the slider bar that separates the _blue_ sections as appropriate

* in step 9, after “Click on the Install Now button” the test case says "The 'Where are you?' screen is displayed" but in reality, two additional interactions happen:

** the “Write previous changes to disk and continue?” modal dialog appears, user clicks on Continue; then
** the “Write the changes to disks?” modal dialog appears, again click Continue

* step 13
** description of state could say that Log in automatically, Require password and Encrypt home options are displayed
** add “Click on the Continue button” before “The Welcome screen is displayed”

* step 18 should say that after the POST, the system offers choice of previous and newly installed system for booting with the currently installed Xubuntu version shown as preselected default