Remove EOD node from haml versions matching ~> 4.0.0

`haml` 4.0.6 was recently released, which breaks the fix implemented in
b504293.

The solution was to use the `Gem::Requirement` class so we always remove
the EOD node for all versions that are in the 4.0.x series.

Change-Id: I75fc7d5036cc5fb870f55ddb8302f772b5e46ead
Reviewed-on: http://gerrit.causes.com/44957
Tested-by: jenkins <jenkins@brigade.com>
Reviewed-by: Shane da Silva <shane.dasilva@brigade.com>