Allow user to select reduced field of view.
This commit replaces the bool 'reduced_fov' parameter with double 'field_of_view'. This allows the user to select what angle of view the laser should publish. Setting this to 180 will have the same effect as setting reduced_fov to 1 previously. Setting it to 260 will remove 5 degrees from the start and end of the scan.
Merge pull request #3 from cburbridge/master

Allow user to select reduced field of view.