works:
1. Add a new PaletteColorView for display circle color in colors grid
2. Add a new ImageHelper used to generated rounded bitmap 
3. Tweak Capture View to introduce a "Palette Card" layout
rename "ImageHelper" to "ImageUtils" to keep the code name consistance
works:
1. Change the theme to always display the action bar (and it is ugly
now!)
2. Add a new method "forceToShowOverflowOptionsOnActionBar()" in
ActivityUtils, so the "more" option works on my Galaxy S4...
add an empty share provider into action bar
works:
1. rename ImageUtils to BitmapUtils
2. add new methods into BitmapUtils
   - saveBitmapToFile()
   - saveBitmapToSDCard()
3. add the permission of WRITE_EXTERNAL_STORAGE
works:
1. Add an "export" function for testing palette card save and export
function
2. Add the "name" property for PaletteData
3. Improve the save bitamp to file function to support create new folder
if the folder doesn't exist
tweak the palette card's appearance