Initial splash screen for setting admin account name, password and management network

This rewrites accuount management to allow changing account name and forces
users to set a reasonable password.
Management network setting, restricting which addresses/networks is allowed
to reach the management interface.

also needs firewall backend to operate.
setup: Validate management network selection
setup: Automatically include your own source IP in management network if not an RFC1918 address
miner setting: Rework how extra settings outside cgminer.conf is stores.

now saved in /config/miner.conf
Apply firewall rules
firewall: In case of wrong IP address ignore the error.
  Previously the whole configuration failed, which resulted
  in firewall rules not applied on start at all.
Miner Remote management servers field
setup: Ignore trailing/leading whitespace in management network
miner: Ignore api-listen. Hardcoded in startup script.
css: fixed password style
miner settings: Clean up save button focus.

also some other minor cleanups.
miner config: Remove unneeded api-network magics. Only clean it up if found.
miner settings: Correct Use BFGMiner checkbox state when using cgminer
backup: Backup the new miner.conf config file
firewall: Apply cgminer access rules
System: Remove misplaced input validation of management network when changing admin password