Move delete_event_handlers_for helper to omega server dsl

Now able to be used by other subsystems
Move sanitize_event_handlers helper to Omega Registry

Now able to be used by all registries
Add helper method to get module classes, couple TODO comments
Add #remove_callbacks methods to Ship and Station
Accept and run events in the manu subsystem
Added check in cosmos for non-existant parent_id

Also added the corresponding test
Raise DataNotFound if cosmos parent not found
Add manufactured SystemJump event, EventHandler for manu subsystem

With this patch a SystemJump event will be raised whenever a ship/
station jumps between systems.
Expand manu event rjr methods to register subsystem event handling

Now manu::subscribe & remove_callbacks handles subsystem events
tracking in addition to entity based events

We may want to pull some of this into the centralized Omega module
at some point allowing other subsystems to leverage the logic
UI: Subscribe/unsubscribe to system_jump events on scene changes
UI: set rjr headers stored server side on session creation

These need to be set before the call to users::login occurs
to that the server can properly store the client rjr endpoint
for security
UI: add helpers to js ship/station to set system (and use them)
Replace system(middleman) w/ exec(middleman) calls in Rakefile

Since Rakefile process doesn't need to be kept around after
middleman is launched, we can replace the entire process
w/ exec instead of launching a shell based subprocess
w/ system (for more concise signal / process handing, etc)

Calls to middleman should be replaced with their full paths
for security in the future
UI: handle system_jump event

Registers entity locally and adds to scene / start tracking
Change RegisteredUser::TYPE to symbol for consistency