new api | workbook reorganizations

* will no longer instance_eval/exec each on each element
* all build execution will now run in the scope of the workbook
* or, if using a builder style approach, the scope of the caller
* this means the workbook will store reference collections and provide an api for adding to and referencing them
new api | style handling changes

* style objects are created, stored, and referenced from the workbook scope
* style directives no longer defined in the scope of the style obj
* workbook proxies style obj directives
new api | element handling changes

* elements are created to validate and store data
* these are then passed to the writer who is responsible for using the data as it sees fit
* all element creation is done in the scope of the workbook
new api | updated markup handling

* mixins, partials, templates, and styles all build in a consistant manner with the new api changes
bundling the latest xmlss
Merge branch 'master' into new-api
Merge branch 'master' into new-api
Merge branch 'master' into new-api

Conflicts:
	Gemfile.lock
notify the writer when making attribute edits from the workbook api
updated xmlss writer to use the lastest Xmlss API

* using the builder render approach
* using the updated Xmlss API that is Osheet compatible
some final cleanups

* adding in to_s, to_data, and to_file workbook meths
* removing all view handler stuff (addresses #17)
* getting name, colspan, rowspan attribute setting hooked up
* updating the examples to run on the new API
updating to use the latest xmlss rc
Merge pull request #19 from kellyredding/new-api

1.0 API
version to 1.0.0.rc.1

* first 1.0 rc
* using the latest xmlss and the new API
updating the README to show creating a workbook with a specific writer
requiring in osheet/mixin by default
updated handling when there is no style class and the default :general format
Merge pull request #20 from kellyredding/rc1-fixes

Rc1 fixes
exported all XmlssWriter concerns to Osheet::Xmlss (https://github.com/kellyredding/osheet-xmlss)
Merge pull request #21 from kellyredding/rm-writer

Moving XmlssWriter concerns to Osheet::Xmlss