Adds additional step for updating config.xml with start page (+1 squashed commits)

Squashed commits:

[0755fac] Remove config.xml parsing logic from windows8 builder script (+1 squashed commits)

Squashed commits:

[73c2d94] Remove start page and whitelists setup logic from wp8_builder.
Fixes PEP checks for master.cfg. Makes pylint happy.
Use FileDownload to transfer config.json from master to slave
Disable file plugin tests for windows8