Add a target_file_ensure parameter to each object type and pass it through to the underlying file resource. The parameter default values are 'file', but having the ensure => parameter of the underlying file type be settable by the user lets people do things like setting target_file_ensure to absent so that they can remove object files via Puppet (instead of manually).

refs#7716 : https://dev.icinga.org/issues/7716
Merge branch 'feature/7716/ensureable_object_params'

refs#7716: https://dev.icinga.org/issues/7716
CHANGELOG updates.
Use %> instead of -%> at the end of some ERB tags so that trailing whitespace isn't surpressed. Surpressing the trailing whitespace caused problems where there was one more parameters listed after each other. Each parameter would get squashed onto a single line, causing a syntax error when Icinga2 parsed the object file.

refs#7715: https://dev.icinga.org/issues/7715
CHANGELOG update.
Merge branch 'fix/7715/template_whitespace_fix'

refs#7715: https://dev.icinga.org/issues/7715
CHANGELOG update.
Fixed an incomplete sentence.
Say what kind of schema is being loaded.
Reword a sentence.
Say what kind of notifications Icinga 2 needs a mail binary for.
Use the parameter names in the sentence for more clarity.
Refactored the enable/disable feature section.
Typos.
Added the target_file_ensure to the list of parameters that's mentioned as settable; also added it to the usage example below.
CHANGELOG update for v0.6.0.
Changed the recommended branch to base pull requests off of.
Merge remote-tracking branch 'upstream/master' into 7713