refactor sidebar to make it more OO

1. instead of re-populate sidebar everytime, we only refresh needed ones
2. improve performances when rendering stuffs
3. break the dependence between sidebar and tracklist, it's cleaner
Merge pull request #103 from EragonJ/refactor/sidebar

refactor sidebar to make it more OO
Changed player time color on dark theme
Windows uninstall previous version before installing new one
Merge pull request #104 from 5punk/master

Windows uninstall previous version before installing new one
Update es-419.ini

Minor fixes and new translations added.
Merge pull request #105 from Pablohn26/patch-1

Update es-419.ini
fix #98, update GA to newest one
fix #108, don't override background directly
update readme 

add one more link to gitter so that users can join our talks easily
Fixed dark theme player cover
Merge pull request #107 from EragonJ/bug/98

fix #98, update GA to newest one
Merge pull request #109 from EragonJ/bug/108

fix #108, don't override background directly
Added splash screen
add missing splash html to build list
bump version to 0.6.5
Added Bountysource
fix #99, can play in background, play any song at any way !

after doing lots of trial and errors, it seems that the code hanged on
node-webkit's request function, and based on nw's different context's
mechanism, I force the code to run under Node's context and this did
fix the problem
Update README.md

I updated download links.
Merge pull request #121 from mimi89999-2/patch-1

Update README.md