Instant Answer: composite units to SI base units instant answer

What does your Instant Answer do?
Converts composite physical quantities (watts, joules, newtons, etc.) to their SI base unit form (some combination of kg, s, m, A, cd).

What problem does your Instant Answer solve (Why is it better than organic links)?
Getting a quick expression for a quantity in si base units makes solving physics problems easier (through unit analysis).

What is the data source for your Instant Answer? (Provide a link if possible)
My data source is a text file in share/goodie/si_units/conversions.txt All the information can be verified correct by this Wikipedia article: http://en.wikipedia.org/wiki/International_System_of_Units

Why did you choose this data source?
I chose this data source because the list of common composite units is short, and will never change. This eliminates the need to rely on a less reliable source (a website that may or may not exist in the future).

Are there any other alternative (better) data sources?
Not that I can think of :(

What are some example queries that trigger this Instant Answer?
"newtons in si units", "si units joules", "watts in si base units"

Which communities will this Instant Answer be especially useful for? (gamers, book lovers, etc)
students, scientists, physics nerds, engineers.

Is this Instant Answer connected to a DuckDuckHack Instant Answer idea?
yep :) https://duck.co/ideas/idea/4725/physical-quantities-in-si-units

Which existing Instant Answers will this one supercede/overlap with?
Perhaps the "conversions" instant answer?

Are you having any problems? Do you need our help with anything?
YES, I am having a bit of trouble with test files. Every time I try to test my instant answer (prove -Ilib t/SiUnits.t) the values that the console spits out for "got" and "expected" are different. Even though I have not made any changes to any of my files. Simply executing the command again changes my output. See below:
![codio_screencap](https://cloud.githubusercontent.com/assets/9040784/5446464/4127cfc0-848d-11e4-850e-cad18ee789de.png)
This having been said, I have thoroughly tested all possibilities by hand, with no issues.

Where did you hear about DuckDuckHack? (For first time contributors)
The link at the bottom of duckduckgo.com :)

What does the Instant Answer look like? (Provide a screenshot for new or updated Instant Answers)
![siunits](https://cloud.githubusercontent.com/assets/9040784/5446484/8b660106-848d-11e4-8db9-dc4756e19778.png)

[x] Added metadata and attribution information (https://duck.co/duckduckhack/metadata)
[x] Wrote test file and added to t/ directory (https://duck.co/duckduckhack/goodie_tests)
[x] Verified that instant answer adheres to design guidelines (https://duck.co/duckduckhack/design_styleguide)
[x] Verified that instant answer adheres to code styleguide (https://duck.co/duckduckhack/code_styleguide)
[x] Tested cross-browser compatibility

    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

Also tested on Arch linux (firefox, and chromium).