support for use_strict

variable appears unused but results in

ReferenceError: flowfile is not defined

when node is invoked with --use_strict
Remove sentiment tip to be consistent
Make node loading more asynchronouse
Updated credentials storage so there is a .._cred.... file per flow.
Allows swapping flows more easily without having to re-enter credentials.
Thus also added *_cred* to .gitignore
Add new/updated Email node including credentials per node.
Deprecating old IMAP node as now part of this general Email node
Tweaks to email error rmessages
Split up nodes.js into components
Fix localfilesystem_spec
Migrate to new node function style
Minify node .html files before sending
Fix node loading order
Tiny formatting tidy ups.
Revert serial port config to a text box - while we look at how best to
provide a list - but allow free input. (for Pi that doesn't enumerate tyAMA0)
Allow serial port to be manual entry or pick from list.
Serial port select combo-box
Remove rogue console.log
Don't show edit dialog for dblclick-drag
Closes #217
Delay node dropping intermediate messages incorrectly
Prevent accidental edit of nodes
Part of #217
Tweaks to shorten Serialport html names.
and remove redundant code.