Add plugin message fallback

Route unmatched messages through plugin fallback handlers

Add observer coverage and bump version to rc.15

utils/version.go

@@ -2,7 +2,7 @@ package utils
 
 const (
 	// VersionString is the module version string.
-	VersionString = "1.0.0-rc.14"
+	VersionString = "1.0.0-rc.15"
 	// VersionMajor is the module major version.
 	VersionMajor = 1
 	// VersionMinor is the module minor version.
@@ -10,5 +10,5 @@ const (
 	// VersionPatch is the module patch version.
 	VersionPatch = 0
 	// VersionBeta is the prerelease counter for the current version.
-	VersionBeta = 14
+	VersionBeta = 15
 )