Move some classes out of com.fsck.k9.mail.store

The classes are just as much related to com.fsck.k9.mail.transport
as com.fsck.k9.mail.store, so having them in
com.fsck.k9.mail.store doesn't seem appropriate.

Move LocalKeyStore to com.fsck.k9.security

Move TrustManagerFactory and TrustedSocketFactory to com.fsck.k9.net.ssl