Reorganize Accounts Folder (#1258)

There's no new code here, just a reorg. Had to change some import calls
in some files to make it all work properly.

Having just done a lot of work in the accounts directory I figured it
could do with some organization. I've broken out all the Header
functions into a different file in order to cut down on the size of the
account.js file.

I also moved the transactions files into a new directory since they are
used by other pages. Also makes them easier to find with this structure.