converted all ajax calls to use Request Payload instead of url params or content data since this apparently is the "correct" way of doing things, at least according to people on stack overflow. This fixes the issue that Govind Soni was having where his server was rejecting url strings with encoded < and > characters. It also fixes the bug I introduced in v4.0 that limits the number of characters on the url string.
Merge branch 'master' into tagsAndCatsFilters