Better UI/UX when we fail to find hush.conf

[leto]

Hush-NG fails pretty hard if it cannot find hush.conf in the default location for each OS it currently supports (mac/linux/win). In a recent commit, it will spew lots of debug info to the JS console instead of throwing an exception and leaving the user with a blank screen. We need much better messaging to the user when something goes wrong and to give them the info they can report back to us easily.

Improvements we could use:

• Allow the user to choose a directory which contains there hush.conf (big win for people with non-standard locations and multiple installs on same machine, like for testnet)
• Ability to start a stopped hushd from initial splash screen
• Show last X lines of debug.log if something goes wrong, if we can find it