Log Message:
Update RMagick to 2.10.0.

Changes:
RMagick 2.10.0
    o ImageMagick releases earlier than 6.3.5-10 and Ruby releases earlier
      than 1.8.5 no longer supported.
    o (Experimental) Support the use of Ruby managed memory for all memory
      allocations (available in ImageMagick 6.5.3-10)
    o Add Image#selective_blur_channel (available in ImageMagick 6.5.0-3)
    o Add new AlphaBackgroundChannel enum value (available in ImageMagick
      6.5.2-5)
    o Add new DistortCompositeOp enum value (available in ImageMagick 6.5.3-7)