The default index isn't created automatically when using
ELK > 5.x. This commit adds a new task into the post-deploy
taskset to force the creation of the default index.

This patch also enforces the kibana config to set index
as defaultIndex without the need for the defaultIndex property
to already exists , preventing the error exposed on the public bug.

Also added a new option named kibana_default_index_options, with
a default index.mapper.dynamic set to true, this option
can be extended by the operator and they will be applied to the index.

Change-Id: Ica63a5fb30947f7ebae6cf8c80500a7dd0907211
Closes-Bug: #1772687
Signed-off-by: Jorge Niedbalski <jorge.niedbalski@linaro.org>