Info on using modifyVars

Brief summary about the function modifyVars.
Fix for usage docs on dumpLineNumbers option
Added link to german translation
Media queries in import statements.
Fixed typos.
Minor change.
Added import variants.
Removed table and changed it to four space indent.
link to ukrainian translation
Add dependency on ruby 1.9.3 as rdiscount doesn't work in 1.9.2
Fix some of the documentation
Added lazy loading of variables.