Add an 'archive' tab to the nav bar

[v0dro]

It would be great to have an additional archives tab that led to http://sciruby.com/blog/archives/.

[Rishabh04-02]

@v0dro Still want to do this?
I want to work on it.

[v0dro]

Sure. go ahead. Do you know how to contribute to an octopress blog?

[Rishabh04-02]

I'll take reference from its documentation.

[v0dro]

Here's what to do anyway:

1. Clone this repo and contribute to the source branch.
2. Make the nav bar modification.
3. Send a PR to the source branch of this repo.

I'll take care of merging it with master and publishing etc.

[Rishabh04-02]

@v0dro Please review #54

[arzoo14]

@v0dro @prasunanand
Is this issue still needs to be resolved?