Fixing issue #258, bad keyfile permissions.

This spits out a warning to the console, but ideally it would also
issue a warning to the GUI for those who didn't start it from the
console. N.B. the warning is a one shot thing, since it fixes the
problem in a way essentially undetectable in the future, so it
should be done right if it is to be done at all.
Maybe we should even disable all keys automatically if the keyfile
is found in an insecure state.
Fix #263 & #262: insecure keyfile permissions.

* Added conditional to keyfile fix code that excludes windows.
* Cleaned up old keyfile permissions fix.
* Added umask (not conditional against Windows, because I don't think that is necessary).
Make warning message more specific.
Merge branch 'master' of https://github.com/Bitmessage/PyBitmessage into keyfile_perm_fix
Merge branch 'master' of https://github.com/Bitmessage/PyBitmessage into keyfile_perm_fix
No paranoid key disable for bad keyfile perms.
Spelling.
Logging fixes.
Merge branch 'master' of https://github.com/Bitmessage/PyBitmessage into keyfile_perm_fix
Merge branch 'no_propagate_loggers' into keyfile_perm_fix

Conflicts:
	src/shared.py
Switch an stderr message to logger.
Clarify IOError handling with comment.
manual merge
manual merge, fix minor import issue
Merge branch 'fiatflux-keyfile_perm_fix' of github.com:Atheros1/PyBitmessage into testperm
Portable mode moves debug.log
Merge pull request #306 from Atheros1/master

Key file permissions