First split into crockery init and crockery run

The init command creates a crockery.db file containing the domain name and
TLS keypair. The run command starts IMAP and SMTP services based on that file.

Supporting only a single domain is starting to look a bit unnecessary. We'll
see how that goes.

vendor/github.com/asdine/storm/index/indexes.go

@@ -0,0 +1,14 @@
+// Package index contains Index engines used to store values and their corresponding IDs
+package index
+
+// Index interface
+type Index interface {
+	Add(value []byte, targetID []byte) error
+	Remove(value []byte) error
+	RemoveID(id []byte) error
+	Get(value []byte) []byte
+	All(value []byte, opts *Options) ([][]byte, error)
+	AllRecords(opts *Options) ([][]byte, error)
+	Range(min []byte, max []byte, opts *Options) ([][]byte, error)
+	Prefix(prefix []byte, opts *Options) ([][]byte, error)
+}