Merge pull request #6 from davidklaw/master

Added the option of specifying standard or retina px units
add
Refactored Spacing
Refactored Spacing
Refactored Spacing
add shape
fixed
add unit
unit fixed bug
fixed
format
menu
shape and text
bus
not fixed
not fixed
Refactored, New features, Sketch 3.0.2 support
README
Merge branch '0.0.2-beta'
fixed bugs