setting the imu settings.accel.scale fails

[aero530]

Using the LSM9DS1_Settings example fails to set the 'settings' values. It appears that the 'begin' function (which is called to apply the settings) is calling the 'init' function. The init function then promptly overwrites the user applied settings with hard coded values.

[bmagistro]

This looks like it may be a duplicate of #27, there is a PR #35 that should address it.