Synchronize locking/unlocking of all keystores.

This change fixes the asynchronous deferred locking that used to be
performed after some timeout after a call to walletpassphrase by
managing the locked state of each account in a new account manager
goroutine.  The timeouts for new unlock requests replace any running
timeouts for older requests, rather than allowing previous timeouts to
expire before the most recent one.

Fixes #105.
Pass even byte length strings to hex.DecodeString.

ok @davecgh
IMPORT PATH MODIFICATION CHANGESET
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Please use this changeset as the first one on top of the conformal codebase.
Note that if there are new imports, they need to be changed as part of this
changeset. In general, use "git rebase" on github.com/conformal's version
and apply this changeset first.
Task #396 on Task Board:

Create a stub websocket call getdepositscript.