Fix app crash handling, provide more debug output when it fails

Summary:
- The check for the crash log file was missing a forward slash at the end of the path (e.g. `ls /storage/emulated` instead of `ls storage/emulated/`)
- Add the output of `adb shell ps` in case the app crash handling fails to provide more debugging information (make it clear whether the process is still alive or not)
- Fix some random typos and extra whitespace

Test Plan:
- `mvn clean install`
- Ran one of the Facebook end-to-end tests.

Reviewers: ainsej, kumar.rangarajan, juyuan.yang.9, asm

Reviewed By: asm

Differential Revision: https://reviews.facebook.net/D28677