upgrade for Bootstrap3 (partial)
remove "label-class" attrib (no usage)
checkbox decorators

add <span class='checkbox'> wrapper for checkboxes (`bootstrap` format)
added include-path

Needed for ZF1's form element decorator plugin loader magic to
find this when used inside apps.
Merge pull request #36 from rwos/bugfix/include-path

added include-path
Merge branch 'master' of https://github.com/easybib/EasyBib_Form_Decorator into bootstrap3
fix: bootstrap file decorators
refactor: change detection of elements to instanceof class (allows custom overriden elements)
fix: setting error class on non-existing element