Add 'Sort by' feature

[Aekal]

In design of category page we have 'Sort by …' select.

We should create this select with logic and add options like:

• Price: low to high
• Price: high to low
• Newest
• *Popularity
• *On sale: show first

[kruchy8]

I would like to take care of this one

[pkarw]

@kruchy8 ok, go on :)