Optimise images (411 KB reduction)

Hi, maintainer.

I've taken the liberty of putting rails_admin's image assets though a range of optimisation tools. Image optimisation allows us to reduce the footprint of images - meaning faster load times at no cost to image quality. It does this by finding the best (lossless) compression parameters, stripping embedded comments, and removing unnecessary colour profiles.

I found 62 optimisable images, making a 411 KB reduction in size. That's about 12.36% of your total image assets.



<table><tr><th>Name</th><th>Reduction</th></tr><tr><td>bg_fallback.png</td><td>93.09%</td></tr><tr><td>icon_sprite.png</td><td>16.63%</td></tr><tr><td>progress_bar.gif</td><td>1.59%</td></tr><tr><td>slider_handles.png</td><td>68.94%</td></tr><tr><td>ui-icons_222222_256x240.png</td><td>15.27%</td></tr><tr><td>ui-icons_454545_256x240.png</td><td>15.27%</td></tr><tr><td>bullet_white.png</td><td>26.37%</td></tr><tr><td>calendar.png</td><td>81.28%</td></tr><tr><td>clock.png</td><td>77.15%</td></tr><tr><td>colorpicker_background.png</td><td>10.28%</td></tr><tr><td>colorpicker_hex.png</td><td>29.32%</td></tr><tr><td>colorpicker_hsb_b.png</td><td>22.68%</td></tr><tr><td>colorpicker_hsb_h.png</td><td>24.41%</td></tr><tr><td>colorpicker_hsb_s.png</td><td>32.79%</td></tr><tr><td>colorpicker_overlay.png</td><td>32.34%</td></tr><tr><td>colorpicker_rgb_b.png</td><td>22.68%</td></tr><tr><td>colorpicker_rgb_g.png</td><td>23.48%</td></tr><tr><td>colorpicker_rgb_r.png</td><td>28.42%</td></tr><tr><td>colorpicker_select.gif</td><td>7.69%</td></tr><tr><td>colorpicker_submit.png</td><td>13.21%</td></tr><tr><td>custom_background.png</td><td>10.86%</td></tr><tr><td>custom_hex.png</td><td>36.65%</td></tr><tr><td>custom_hsb_b.png</td><td>27.44%</td></tr><tr><td>custom_hsb_h.png</td><td>26.49%</td></tr><tr><td>custom_hsb_s.png</td><td>24.91%</td></tr><tr><td>custom_rgb_b.png</td><td>28.27%</td></tr><tr><td>custom_rgb_g.png</td><td>27.03%</td></tr><tr><td>custom_rgb_r.png</td><td>28.59%</td></tr><tr><td>custom_submit.png</td><td>14.44%</td></tr><tr><td>select.png</td><td>47.83%</td></tr><tr><td>select2.png</td><td>41.12%</td></tr><tr><td>slider.png</td><td>23.81%</td></tr><tr><td>logo.png</td><td>54.82%</td></tr><tr><td>magnifier.png</td><td>40.35%</td></tr><tr><td>icon_sprite.png</td><td>16.63%</td></tr><tr><td>ui-icon-circle-triangle-n-dark.png</td><td>75.18%</td></tr><tr><td>ui-icon-circle-triangle-n-light.png</td><td>64.78%</td></tr><tr><td>ui-icon-circle-triangle-s-dark.png</td><td>75.34%</td></tr><tr><td>ui-icon-circle-triangle-s-light.png</td><td>64.78%</td></tr><tr><td>bg_fallback.png</td><td>93.09%</td></tr><tr><td>icon_sprite.png</td><td>16.63%</td></tr><tr><td>progress_bar.gif</td><td>1.59%</td></tr><tr><td>slider_handles.png</td><td>68.94%</td></tr><tr><td>ui-icons_222222_256x240.png</td><td>15.27%</td></tr><tr><td>ui-icons_454545_256x240.png</td><td>15.27%</td></tr><tr><td>dashboard.png</td><td>36.51%</td></tr><tr><td>delete.png</td><td>39.47%</td></tr><tr><td>list.png</td><td>35.48%</td></tr><tr><td>nested.png</td><td>34.58%</td></tr><tr><td>polymorphic.png</td><td>41.38%</td></tr><tr><td>10_36_27_888_Pensive_Parakeet.jpg</td><td>6.99%</td></tr><tr><td>08_54_39_906_Costa_Rican_Frog.jpg</td><td>5.50%</td></tr><tr><td>Boston City Flow.jpg</td><td>6.26%</td></tr><tr><td>Boston City Flow.jpg</td><td>34.57%</td></tr><tr><td>Costa Rican Frog.jpg</td><td>5.50%</td></tr><tr><td>Costa Rican Frog.jpg</td><td>0.39%</td></tr><tr><td>Boston_City_Flow.jpg</td><td>6.26%</td></tr><tr><td>thumb_Boston_City_Flow.jpg</td><td>27.75%</td></tr><tr><td>Costa_Rican_Frog.jpg</td><td>5.50%</td></tr><tr><td>thumb_Costa_Rican_Frog.jpg</td><td>1.23%</td></tr><tr><td>Pensive_Parakeet.jpg</td><td>6.99%</td></tr><tr><td>thumb_Pensive_Parakeet.jpg</td><td>2.76%</td></tr></tr></table>