Add support for run only once #227
Description
Sometimes you would like to control externally (using a crontab) for example, how often you want to scan an index a hard drive.
Also, you might want to do it only once so you don't need to "watch" for changes.
In such a case, waiting for a message in logs is far from being ideal.
Let's add a new option loop which defines the number of runs we want before exiting:
Xwhere X is a negative value means infinite, like-1(default)0means that we don't run FSCrawler. Well... Not sure what could be the usage. May be checking that the configuration file is correct?Xwhere X is a positive value is the number of runs before it stops.
If you want to scan your hard drive only once, run with --loop 1.
Based on #223 (comment)