crash_reporter: Fix a couple crash_sender issues

- Added grep to the list of required modules.
- Run crash_sender with the 'system' group to allow calls to
  metrics_client to read both metrics files owned by system and
  crash_reporter files owned by root.
- Fix periodic_scheduler's check delay to actually be 5 minutes.

Bug: 23122375
Change-Id: Iff214c4e591a676a516162a92ea5aedcf0824f46
diff --git a/crash_reporter/init.crash_reporter.rc b/crash_reporter/init.crash_reporter.rc
index db9bb6f..30e87f5 100644
--- a/crash_reporter/init.crash_reporter.rc
+++ b/crash_reporter/init.crash_reporter.rc
@@ -27,3 +27,4 @@
 service crash_sender /system/bin/periodic_scheduler 3600 14400 crash_sender \
     /system/bin/crash_sender
     class late_start
+    group system