UI redesign

[rexim]

I've made a quick temporary design. Do we need to invest more time in this and make something really cool? If so, we can close #1.

[ForNeVeR]

Personally I like the current version. Maybe we just should use slightly less acidic colors.

[rexim]

If we are going to make a new design we should consider the following:

• the design should come in two variants: light and dark, so people with different preferences could pick what they like;
• the base colors of the design should be changable input parameters, so we can easily play with them and pick ones that we like the most. To achive this we could use CSS preprocessors like LESS. Using the approach we can define light and dark variants of the design simply by changing its input parameters.
• the design should be defined as one (I don't think that more is required) CSS or LESS (or another CSS preprocessor) and resources (like images) associated with it.

[rexim]

It would be great to resolve #5 in the scope of this task if possible.