Add autosuspend_policy config setting
Display plugin uses autosuspend_policy setting

Autosuspend policy is modified based on the
value of autosuspend_policy config setting.
Mcetool can be used to modify autosuspend_policy configuration

Added new option for mcetool:
 -s, --set-suspend-policy=MODE
    set the autosuspend mode; valid modes are:
    "enabled", "disabled" and "early"
Merge pull request #33 from spiiroin/suspend_config

Added configuration item for disabling automatic suspend