Move ipfs daemon start/stop code from replay to util

[machawk1]

No description provided.

[machawk1]

Also, handle ipfs init from the start code if it has not be done already.

[machawk1]

One of the barriers to moving this function is that it is dependent on the IPFS HTTP Client, which is global. This likely hints at a larger underlying problem. Does the client need to be global to have the pseudo-singleton accessible from all functions?

The same global object is also used for .cat()ing multihashes from IPFS.

[machawk1]

The global was removed in #640 in favor of a function call to util to obtain the client. The same goes with the .cat()s in replay.