Add Confluence markup format parameter
Add Confluence markup format parameter

It will allow to create Confluence pages that will be interpreted
with the wiki markup syntax.

More info about Confluence formats here:
https://confluence.atlassian.com/doc/confluence-markup-283640216.html

Change-Id: I2534634a1b1eec1b9d970e5a055b8e73735fd8c9

AstroTech/atlassian-python-api,AstroTech/atlassian-python-api,MattAgile/atlassian-python-api