Use keyword argument for boolean flags

Using keyword arguments makes the intent of the code clearer, due to
the fact that a name is attached to a boolean value, making the
reasoning about the code easier.

Change-Id: I0dd05fa521ed8bbaf1c6dbd7a3e554384642c1f4
Fix tests mocking bug when doing regex search

Change-Id: I7a6d8b5e111884e2c3017df82bc447ba4e99905c
Add support for EC2 config scripts

The userdatautils plugin now supports EC2 formatted scripts.
It consists of multiple batch or powershell scripts enclosed
into specific tags, where the batch part is executed before
the powershell one.

Change-Id: Ic9b2c73838c606d3eeaf039363dbdf46313379ca