Bug 1851288: URL encode the . char in block title

Along with the other special chars as we use it as an array key and
PHP changes . to _

behatnotneeded

Change-Id: I22125a539bb205b8e1bc036c4ceee995d19ffb73
Signed-off-by: Robert Lyon <robertl@catalyst.net.nz>
(cherry picked from commit f4360be786ef2ffa3e0debfb4da32a235afcf98b)