Only people building Unity plugins will need to import the asset store tools plugin into their project, and it's a toss up whether they want to commit the tooling into their repo (they might or they might not want to, it highly depends on their workflow). The default .gitignore shouldn't be making this choice for these users.
Unity projects targeting the 2.0/3.5 runtime or built with mono < v5.0 generate `mdb` files, not `pdb` files.
Looks like the `crashlytics-build.properties` gets around in more than just the `StreamingAssets` folder, looking at [examples around the internets](https://github.com/auth0/sharelock-android/blob/master/app/src/main/assets/crashlytics-build.properties), so it should probably just be ignored as a filename.