Add Spices for Bitcoin blocks, transactions and addresses

![bitcoin_address](https://cloud.githubusercontent.com/assets/5072010/3424524/1d1021b6-ffd4-11e3-8639-b0e32b348b8b.png)
![bitcoin_block](https://cloud.githubusercontent.com/assets/5072010/3424523/1d08bc6e-ffd4-11e3-85de-0fbd420d2198.png)
![bitcoin_transaction](https://cloud.githubusercontent.com/assets/5072010/3424525/1d144ce6-ffd4-11e3-9139-00692196ce7f.png)

**What does your instant answer do?**
Spices for showing information about Bitcoin addresses, blocks and transactions based on the Biteasy.com Blockchain API.

**What are some example queries that trigger this instant answer?**
* 000000000000000036a908fa64c2656f5e33e51050833c73866a81315ca75216
* ebf42a5fb9b87e73c740fe45cd016d6b17beac3d764fc9952e54d5cda64bfca6
* 1Biteasym3p5E4soZq8So6NjkjYugEnz2X

**What is the data source for your instant answer? (Provide a link if possible)**
https://www.biteasy.com

**Which communities will this instant answer be especially useful for? (gamers, book lovers, etc)**
Definitely useful for the bitcoin community

**Which existing instant answers will this one supersede/overlap with?**
There is no other spice for the transactions or the blocks. There is however a spice called BitcoinBalance but we believe that our version is more complete.

**Is this instant answer connected to a DuckDuckHack instant answer idea?**
I don't think so. I haven't seen anything in the ideas forum.

**Are you having any problems? Do you need our help with anything?**
Everything seems ok on our side. If there are proposed changes we will happily make them.

## Checklist
Please place an 'X' where appropriate.

```
[X] Added metadata and attribution information
[X] Wrote test file and added to t/ directory
[X] Verified that instant answer adheres to design guidelines(https://github.com/duckduckgo/duckduckgo-documentation/blob/master/duckduckhack/styleguides/design_styleguide.md)
[] Tested cross-browser compatability

    Please let us know which browsers/devices you've tested on:
    - Windows 8
        [] Google Chrome   
        [] Firefox         
        [] Opera           
        [] IE 10           

    - Windows 7
        [] Google Chrome   
        [] Firefox         
        [] Opera           
        [] IE 8            
        [] IE 9            
        [] IE 10           

    - Windows XP
        [] IE 7            
        [] IE 8            

    - Mac OSX
        [X] Google Chrome   
        [X] Firefox         
        [X] Opera           
        [X] Safari          

    - iOS (iPhone)
        [] Safari Mobile   
        [] Google Chrome   
        [] Opera           

    - iOS (iPad)
        [] Safari Mobile   
        [] Google Chrome   
        [] Opera            

    - Android
        [] Firefox         
        [] Native Browser  
        [] Google Chrome   
        [] Opera
```
Same here, we should probably account for any terms users might enter alongside the numbers