Set a default username/password

Set a default username of `php-thrift-sql` when there is no username given for either Hive or Impala.

Also set a default password for Hive if none given. With SASL Hive just needs something set to not error out which prevents some common problems when using this lib. This closes #22 and closes #23.

src/ThriftSQL.php

@@ -1,6 +1,9 @@
 <?php
 
 abstract class ThriftSQL {
+
+  const USERNAME_DEFAULT = 'php-thrift-sql';
+
   /**
   * @return self
   * @throws \ThriftSQL\Exception

src/ThriftSQL/Hive.php

@@ -31,6 +31,15 @@ public function connect() {
     if ( null !== $this->_sessionHandle ) {
       return $this;
     }
+
+    // Make sure we have auth info set
+    if ( empty( $this->_username ) ) {
+      $this->_username = self::USERNAME_DEFAULT;
+    }
+    if ( empty( $this->_password ) ) {
+      $this->_password = 'ANY-PASSWORD';
+    }
+
     try {
       $this->_transport = new \Thrift\Transport\TSocket( $this->_host, $this->_port );
       if ( null !== $this->_timeout ) {
@@ -51,10 +60,9 @@ public function connect() {
         )
       );
       $TOpenSessionReq = new \ThriftGenerated\TOpenSessionReq();
-      if ( null !== $this->_username && null !== $this->_password ) {
-        $TOpenSessionReq->username = $this->_username;
-        $TOpenSessionReq->password = $this->_password;
-      }
+      $TOpenSessionReq->username = $this->_username;
+      $TOpenSessionReq->password = $this->_password;
+
       // Ok, let's try to start a session
       $this->_sessionHandle = $this
         ->_client

src/ThriftSQL/Impala.php

@@ -26,6 +26,11 @@ public function connect() {
       return $this;
     }
 
+    // Make sure we have a username set
+    if ( empty( $this->_username ) ) {
+      $this->_username = self::USERNAME_DEFAULT;
+    }
+
     try {
       $this->_transport = new \Thrift\Transport\TSocket( $this->_host, $this->_port );