Merge pull request #7 from siddacious/master

updated buffer passed to unpack to address #6

Author: ladyada

adafruit_adxl34x.py

@@ -386,7 +386,7 @@ def _read_register(self, register, length):
         with self._i2c as i2c:
             i2c.write(self._buffer, start=0, end=1)
             i2c.readinto(self._buffer, start=0, end=length)
-            return self._buffer
+            return self._buffer[0:length]
 
     def _write_register_byte(self, register, value):
         self._buffer[0] = register & 0xFF