Transport for London line status

**What does your instant answer do?**
Shows the Transport for London (TfL) line status for the Tube, Bus, Docklands Light Railway (DLR), Overground and other lines.

**What problem does your instant answer solve (Why is it better than organic links)?**
Organic links for the searches below involve navigating to tfl.gov.uk homepage and scrolling to find the line of interest. 

**What is the data source for your instant answer? (Provide a link if possible)**
The TfL API at http://api.tfl.gov.uk, specifically the line status endpoint /Line/{lineId}/Status

**Why did you choose this data source?**
TfL own this data, so they are the canonical source for it. It should have a lower latency and better correctness than secondary sources. Also, I helped build the API so I know how it works :)

**Are there any other alternative (better) data sources?**
No.

**What are some example queries that trigger this instant answer?**
Victoria line status
Hammersmith City line status
271 line status
DLR line status
Overground line status

(Any line name taken from the homepage of tfl.gov.uk should work. The trigger is ends-with "line status")

**Which communities will this instant answer be especially useful for? (gamers, book lovers, etc)**
This will be especially useful for London commuters and tourists.

**Is this instant answer connected to a DuckDuckHack [instant answer idea](https://duck.co/ideas)?**
Yes - I submitted an idea at https://duck.co/ideas/idea/1146/london-tube-line-status that got a few upvotes.

**Which existing instant answers will this one supersede/overlap with?**
None, hopefully!

**Are you having any problems? Do you need our help with anything?**
Not right now! Although I didn’t quite manage to cover all of the browser/OS combinations in cross-browser testing. However, the handlebars template is really simple so I think I’ll be OK.

**\*\*Note:** Please attach a screenshot for new instant answer pull requests, and for pull requests which modify the look/design of existing instant answers.

## 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)
[X] Tested cross-browser compatibility

    Please let us know which browsers/devices you've tested on:
    - Windows 8
        [X] Google Chrome   
        [X] Firefox         
        [X] Opera           
        [X] IE 10           

    - Windows 7
        [X] Google Chrome   
        [X] Firefox         
        [X] Opera           
        [] IE 8            
        [X] IE 9            
        [X] IE 10           

    - Windows XP
        [] IE 7            
        [] IE 8            

    - Mac OSX
        [X] Google Chrome   
        [X] Firefox         
        [X] Opera           
        [X] Safari          

    - iOS (iPhone)
        [X] Safari Mobile   
        [X] Google Chrome   
        [X] Opera           

    - iOS (iPad)
        [X] Safari Mobile   
        [X] Google Chrome   
        [X] Opera            

    - Android
        [] Firefox         
        [X] Native Browser  
        [X] Google Chrome   
        [] Opera
```
![screen shot 2014-07-21 at 18 38 18](https://cloud.githubusercontent.com/assets/6024877/3661286/1c9d626e-11bf-11e4-8bd6-e5245ac93e57.png)
![screen shot 2014-07-21 at 18 37 42](https://cloud.githubusercontent.com/assets/6024877/3661303/3a7480d8-11bf-11e4-98a9-fba37c4fa3ae.png)

Would compare it like:

```perl
lc($_) =~ /overground/
```

It's more idiomatic and it's easy to miss `"overground"` as regexp since it's colored differently in text editors.