Bug 13691: Add basic selenium script

Bug 13691: Add basic selenium script

This script has been used to compare 3.16.x and 3.18.x performances on
bug 13690.

What it does:
- Go on the mainpage and process a log in
- Create a patron category
- Create a patron
- Add 3 items
- check the 3 items out to the patron
- check the 3 items in

How to use it?

$ wget https://selenium-release.storage.googleapis.com/2.53/selenium-server-standalone-2.53.0.jar

$ vim /etc/apt/sources.list.d/firefox.list
  deb http://packages.linuxmint.com debian import
$ apt-get update
$ apt-get install firefox
$ sudo apt-get install xvfb

$ SELENIUM_PATH=/home/koha/tools/selenium-server-standalone-2.53.0.jar
$ Xvfb :1 -screen 0 1024x768x24 2>&1 >/dev/null &
$ DISPLAY=:1 java -jar $SELENIUM_PATH

perl t/db_dependent/selenium/basic_workflow.t

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Note the pages have changed so the tests will not all pass.
Also you need Selenium::Remote::Driver installed and staffClientBaseURL
must be set

I will change the tests in a follow up patch.
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>