Update quantities.js

- added PostScript point length unit
- see http://en.wikipedia.org/wiki/PostScript_point
- 1 PostScript point = 0.000352777778 meters
Update quantities.js

- updated pica and point length units to contemporary desktop publishing standard
- current units are Traditional American standard
- the contemporary standard is more likely to be the desired unit
- http://en.wikipedia.org/wiki/Point_(typography)
- 1 point = 0.000352777778 meters
- http://en.wikipedia.org/wiki/Pica_(typography)
- 1 pica = 0.00423333333 meters
Merge pull request #6 from rjanicek/master

Fix pica/point definitions
Fix #8: Allow to initialize unitless quantity with an empty string
Fix JSHint warnings in specs
Throw an error instance instead of a plain string (fix #7)

It allows to get a stacktrace to the error's origin
Cache conversion results from Qty#to instead of Qty#toString
Do not use snake_case
Add release-prepare script
Release 1.2.0
Implement faster way to count decimals

Parsing strings to get decimals is a lot slower!
Remove nodejs 0.6 from Travis config