installer: use predefined resource_limits if present

If there is a canned resource_limits.conf.$profile{,.$type} file in
/etc/openshift that matches the profile specified for the node,
openshift.sh will use it from the start by copying it over the default
resource_limits.conf.

Also introduces $CONF_NODE_HOST_TYPE so the above can specify
different resource_limits for different host sizes/flavors.
admin scripts: script to run conn hooks for mongodb carts

This commit adds run-mongodb-connection-hooks.rb, intended to be run on
the broker, which automates running the connection hooks for any app
using the mongodb-2.4 add-on cartridge. This is specifically to update
the `PATH` and `LD_LIBRARY_PATH` variables for scaled carts after
updating to a new version of the `openshift-origin-cartridge-mongodb`
package.

Enterprise bug 1135062
https://bugzilla.redhat.com/show_bug.cgi?id=1135062
Merge pull request #442 from sosiouxme/default-profiles

installer: use profile resource_limits if present
Merge pull request #446 from dobbymoodge/sclmongo

admin scripts: script to run conn hooks for mongodb carts