Keys: Fix browser data types

lib/privatekey.js

@@ -39,7 +39,7 @@ var PrivateKey = function PrivateKey(data, network, compressed) {
     info.bn = PrivateKey._getRandomBN();
   } else if (data instanceof BN) {
     info.bn = data;
-  } else if (data instanceof Buffer) {
+  } else if (data instanceof Buffer || data instanceof Uint8Array) {
     info = PrivateKey._transformBuffer(data, network, compressed);
   } else if (typeof(data) === 'string'){
     info = PrivateKey._transformWIF(data, network, compressed);

lib/publickey.js

@@ -36,7 +36,7 @@ var PublicKey = function PublicKey(data, compressed) {
     info.point = data;
   } else if (typeof(data) === 'string'){
     info = PublicKey._transformDER(new Buffer(data, 'hex' ));
-  } else if (data instanceof Buffer){
+  } else if (data instanceof Buffer || data instanceof Uint8Array){
     info = PublicKey._transformDER(data);
   } else if (data.constructor && (data.constructor.name && 
                                   data.constructor.name === 'PrivateKey')) {
@@ -90,7 +90,7 @@ PublicKey._transformPrivateKey = function(privkey) {
  */
 PublicKey._transformDER = function(buf){
   var info = {};
-  if (!(buf instanceof Buffer)){
+  if (!(buf instanceof Buffer) && !(buf instanceof Uint8Array)){
     throw new TypeError('Must be a hex buffer of DER encoded public key');
   }