add Checkey from Guardian Project using verified build and upstream key

This includes the new verification process where the upstream's APK
signature is used in the f-droid.org repo.

metadata/info.guardianproject.checkey.txt

@@ -0,0 +1,30 @@
+Categories:Development
+License:GPLv3
+Web Site:https://dev.guardianproject.info/projects/checkey
+Source Code:https://github.com/guardianproject/checkey
+Issue Tracker:https://dev.guardianproject.info/projects/checkey/issues
+Bitcoin:1Fi5xUHiAPRKxHvyUGVFGt9extBe8Srdbk
+
+Auto Name:Checkey
+Summary:Info on local apps
+Description:
+Checkey is a utility for getting information about the APKs that are installed
+on your device. Starting with a list of all of the apps that you have
+installed on your device, it will show you the APK signature with a single
+touch, and provides links to virustotal.com and androidobservatory.org to
+easily access the profiles of that APK. It will also let you export the
+signing certificate and generate ApkSignaturePin pin files for use with the
+TrustedIntents library.
+.
+
+Repo Type:git
+Repo:https://github.com/guardianproject/checkey.git
+Binaries:https://guardianproject.info/releases/Checkey-%v.apk
+
+Build:0.1.1,101
+    commit=0.1.1
+
+Auto Update Mode:Version %v
+Update Check Mode:Tags
+Current Version:0.1.1
+Current Version Code:101