First commit of BPM to ms converter Goodie

# Goodie Pull Request Template

Using this template will help us better understand your Instant Answer and assist you when necessary.  Simply copy and paste the markdown below into the description of your GitHub pull request and complete as appropriate.

**What does your Instant Answer do?**
It converts BPM (beats per minute) into note values in milliseconds. It is useful in musical applications for example when needing to calculate delay times, reverb times, compressor attack and release settings etc.

**What problem does your Instant Answer solve (Why is it better than organic links)?**
There exists sites with bmp to ms calculators but it is more convenient to get the results directly in the search engine.

**What is the data source for your Instant Answer? (Provide a link if possible)**
The calculation is done inside the Perl script.

**What are some example queries that trigger this Instant Answer?**
120 bpm to ms
90 bpm to ms

**Which communities will this Instant Answer be especially useful for? (gamers, book lovers, etc)**
Music performers and recording communities.

**Is this Instant Answer connected to a DuckDuckHack [Instant Answer idea](https://duck.co/ideas)?**
No

**Are you having any problems? Do you need our help with anything?**
I did not seem to be able to write a test file for the html, only the plain-text answer.

**What does the Instant Answer look like? (Provide a screenshot for new or updated Instant Answers)**
![bpmtoms_example](https://cloud.githubusercontent.com/assets/7037005/5280422/8962befa-7af9-11e4-8bcb-eba73b97abff.jpg)


## Checklist
Please place an 'X' where appropriate.

```
[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
        [x] Google Chrome
        [x] Firefox
        [] IE 7
        [x] IE 8

    - Mac OSX
        [] Google Chrome
        [] Firefox
        [] Opera
        [] Safari

    - iOS (iPhone)
        [x] Safari Mobile
        [] Google Chrome
        [] Opera

    - iOS (iPad)
        [] Safari Mobile
        [] Google Chrome
        [] Opera

    - Android
        [] Firefox
        [] Native Browser
        [] Google Chrome
        [] Opera
```
Can we add some negative tests for the triggers. I.e.
`"-1 bpm to ms" => undef`
`"some bpm in ms" => undef`
Also one for another value (i.e. != 120) would be nice