Add a quick way to transfer civilian => imperial

[matthewhively]

Call it conscription. It'll cost a minimal amount of CP, but a fair chunk of money.
It can use a defunct DE Freighter graphic? (or something else?)
It should have essentially zero movement speed in battle, and no FTL capability. (though I guess hiver can still transfer via gates)

Its only purpose is to bring captured colonies up to speed a bit faster (since they start with 100 imperial). Growth rate is fairly slow first dozen turns, so being able to transfer 100k after 1 turn would help tremendously.