lite: Add synchronization in lite verify (#2396)

* Implement issues 2386: add synchronization in lite verify and change all Certify to Verify

* Replace make(chan struct{}, 0) with make(chan struct{})

* Parameterize memroy cache size and add concurrent test

* Refactor import order

lite/proxy/query.go

@@ -146,7 +146,7 @@ func GetCertifiedCommit(h int64, client rpcclient.Client, cert lite.Verifier) (t
 			h, sh.Height)
 	}
 
-	if err = cert.Certify(sh); err != nil {
+	if err = cert.Verify(sh); err != nil {
 		return types.SignedHeader{}, err
 	}