grab: Use JPEG quality setting "95" instead of "100"

A setting of 100 is purely academic, it creates bigger files but pixels
hardly differ more than a single lsb compared to a 95 setting.
grab: Avoid evil os.system, run async, release resources

os.system uses too many resources, eConsoleApp is much safer.
This also makes the request run asynchronous.
Clean up the temporary file after completion.
grab: Don't invoke a shell

Pass arguments directly to the subprocess, and don't start a shell to
parse them first. This also prevents shell injection attacks, because
the arguments are passed on directly. It's also faster because it
avoids an exec call.
Merge pull request #6 from E2OpenPlugins/master

merge with main project