receiver: Send a single INVALID_MAJOR_VERSION notify for IKE version > 2

We sent both a notify using IKEv1 and IKEv2. This is a little more aggressive
than required, RFC 5996 says we "SHOULD send an unauthenticated Notify
message of type INVALID_MAJOR_VERSION containing the highest (closest) version
number it supports".

Fixes #657.
starter: Fix memory leaks and warn if conn/ca sections are ignored due to parse errors
android: Use correct tag to define category for CREATE_SHORTCUT intent-filter
android: Remove unused hash argument from getTrustedCertificates()
android: Add utility method to convert a byte array to a hex string
android: Target latest SDK version
android: Subclass Application to provide static access to the application context
android: Move TrustedCertificateEntry to a new package
android: Add local certificate store

The class manages certificates stored in files within the app's
private data directory.
android: Add KeyStoreSpi implementation that uses LocalCertificateStore
android: Add Provider for the local certificate store
android: Register local certificate store provider when the app is initialized
android: Cache certificates from multiple KeyStores

Including the new local one.
android: Change how CA certificates from different sources are accessed
android: Allow selection of local certificates
android: Set action when using TrustedCertificatesActivity to select a certificate
android: Only close TrustedCertificatesActivity on click when selecting a certificate
android: Replace option to reload CA certificates with CA certificate view

The reload option will be added there.
android: Add option to reload CA certificates to TrustedCertificatesActivity
android: Change how CA certificate reloads are initiated