Vulnerability in light client proxy (#1081)

* Vulnerability in light client proxy

When calling GetCertifiedCommit the light client proxy would call
Certify and even on error return the Commit as if it had been correctly
certified.

Now it returns the error correctly and returns an empty Commit on error.

* Improve names for clarity

The lite package now contains StaticCertifier, DynamicCertifier and
InqueringCertifier. This also changes the method receivers from one
letter to two letter names, which will make future refactoring easier
and follows the coding standards.

* Fix test failures

* Rename files

* remove dead code

lite/proxy/wrapper.go

@@ -15,14 +15,14 @@ var _ rpcclient.Client = Wrapper{}
 // provable before passing it along. Allows you to make any rpcclient fully secure.
 type Wrapper struct {
 	rpcclient.Client
-	cert *lite.Inquiring
+	cert *lite.InquiringCertifier
 }
 
 // SecureClient uses a given certifier to wrap an connection to an untrusted
 // host and return a cryptographically secure rpc client.
 //
 // If it is wrapping an HTTP rpcclient, it will also wrap the websocket interface
-func SecureClient(c rpcclient.Client, cert *lite.Inquiring) Wrapper {
+func SecureClient(c rpcclient.Client, cert *lite.InquiringCertifier) Wrapper {
 	wrap := Wrapper{c, cert}
 	// TODO: no longer possible as no more such interface exposed....
 	// if we wrap http client, then we can swap out the event switch to filter
@@ -34,7 +34,9 @@ func SecureClient(c rpcclient.Client, cert *lite.Inquiring) Wrapper {
 }
 
 // ABCIQueryWithOptions exposes all options for the ABCI query and verifies the returned proof
-func (w Wrapper) ABCIQueryWithOptions(path string, data data.Bytes, opts rpcclient.ABCIQueryOptions) (*ctypes.ResultABCIQuery, error) {
+func (w Wrapper) ABCIQueryWithOptions(path string, data data.Bytes,
+	opts rpcclient.ABCIQueryOptions) (*ctypes.ResultABCIQuery, error) {
+
 	res, _, err := GetWithProofOptions(path, data, opts, w.Client, w.cert)
 	return res, err
 }