Exclamation points in filenames cause creation of infinite duplicates in Google Drive

[sorentycho]

Steps to reproduce:

1. Create a file or directory whose name contains an exclaimation point: Cool! File! Name!
2. Wait for sync to happen
3. Sync never completes, and infintely many copies of the directory get created in Google Drive

The only way to end the endless sync is to both disconnect the Google Drive backend and delete remoteStorage.js's IndexedDB. It's likely that other characters (including space?) cause the issue to manifest as well, but considering the cost of testing I'm reluctant to try.