Show progress using '.'

This will add a progress bar using '.' characters, using generators to report suspicious files as they are seen.

Example output:
```
WireLurker Detector (version 1.0.0)
Copyright (c) 2014, Palo Alto Networks, Inc.

[+] Scanning for known malicious files
.................
[-] Nothing is found.
[+] Scanning for known suspicious files
..
[-] Nothing is found.
[+] Scanning for infected applications (may take minutes)
....................................................................................................................................................................................
[-] Nothing is found.
[+] Your OS X system isn't infected by the WireLurker. Thank you!
```