CSS green purple

I have modified the CSS files to make the colors more harmonious :
- Soft purple on the background, 
- disappearance of the blue color on buttons replaced by the same greens existing
- On welcome page (login page) transparency of the login page with customizable background image

You have to put a background image in folder : 

```
\xbmc-video-server\src\images\
```
And the name of background image must be named as : 

```
bg.jpg
```
Like that : 

```
\xbmc-video-server\src\images\bg.jpg
```
Two CSS files must be replaced :

```
login-min.css
styles-min.css
```

In folder : 

```
\xbmc-video-server\src\css
```