Bug-51: UI refresh

Do the following:
1. Change project theme.
2. Change buttons style.
3. Use font to display icon.
4. Other UI Adjustment.
How about to create a function to concat white space and the string at the same time? Like:
```
IconFontUtils.get(IconFontUtils.REMOVE, context.getString(R.string.button_delete));
```
The whitespace concatenation is a little bit ugly.