The mpercolate api rest endpoint should also support http get.
Fixed bug (NPE) in mpercolate api, defaults from percolating existing documents where also applied for the regular percolate api, these defaults were none existing (null).
[DOCS] Fixed percolate docs errors
Randomize exceptions when file is deleted while still open.

This somehow emulates a behavior on windows but we should test the
other code paths as well.