ditch ActionMode and put actions into ActionBar

This also moves AppListFragment into MainActivity as a static inner class
to simplify the code.
first stab at generating a .java file for a certificate pin
certificate view: add MD5, SHA1, SHA-256, Key algo/bit, Signing algo
move getCertificateFingerprint() to Utils since its static
switch to appcompat theme to support older devices

oops, forgot to switch this before...
enable menu items on ActionBar and reorder for most commonly used
final format for generating .java file for ApkSignaturePin subclass

This is the output of "Generate Pin": it is a .java file that is a subclass
of info.guardianproject.trustedintents.ApkSignaturePin.  It is used to pin
sending and/or receiving of Intents to APKs signed by the represented
signing key.
include fingerprints in generated pin .java files for double-checking

Including the fingerprint in the ApkSignaturePin subclass provides a way to
double-check that the APK signature was properly transcribed to the inline
java byte[][] code.