[FEATURE getElementById] Introduces getElementById
Merge pull request #208 from chadhietala/getElementById

[FEATURE getElementById] Introduces getElementById
[BUGFIX] Allow for alternative rootNode for getElementById
Make plugins an object.
Merge pull request #210 from rwjblue/update-syntax-walker-protocol

Make plugins an object.
Bump version.
Merge pull request #209 from chadhietala/default-document

[BUGFIX] Allow for alternative rootNode for getElementById
Automated cross-browser testing