Add .gitignore as text as well

.gitignore files are not project dependent, rather any git projects may have them. Since they are text files, it's better to treat them as such.
Create WordPress.gitattributes

These settings are for WordPress.

However, any attribute that may generally be considered as appropriate for web, may also be added here.
Update the main .gitattributes

Correctly placing .gitignore as text as well. People forking this project from different environment may customize their own .gitignore file without worrying about autocrlf setting.
Merge pull request #4 from fayazmiraz/master

Added WordPress.gitattributes file