Merge pull request #76 from inspiran/master

small syntax fix
cs
Merge pull request #77 from cordoval/patch-4

cs
remove unneeded use statements
Delete README.markdown

let's move forward guys
Merge pull request #78 from cordoval/patch-4

remove unneeded use statements
Merge pull request #80 from cordoval/patch-6

Delete README.markdown
Update README.md
plug document interface and clean up missing errors
switch name to itemableinterface
plug 55 and keep 54 like a pro
plug phpunit and change travis to run tests
restore invoice item and item interface
bootstrap base item class implementing common interface and items implementation implementing separate interfaces
removing couple of methods plugged into order item
intefaces extending base interface
not sure if this is the right direction
iampersistent helped me to sort this out
back to green
refactor common methods to item base