Adds a few useful scripts for auto upload and periodic download sync

Not sure if you are interested, but if so you are welcome to include these scripts.

1) grive-incron allows you to launch grive from an incron script to automatically push changes to Google drive. The script ignores the .grive and .grive-sync files. It also prevents two copies of grive from running at once for the same user (didn't do it per directory, but that might have been smarter).

2) Example incron and crontab lines to allow grive-incron to push files as they change and for periodic sync to catch any changes made online or elsewhere.