Fixes language switch for overview layouts

See scala/scala.github.com#129
Merge pull request #135 from vjovanov/am-fixes

Minor fixes to the Actor migration kit. 
Adds Coursera Statistics blog article
Merge branch 'news', adds Coursera statistics article
docs for macros
Merge pull request #136 from xeno-by/master

docs for macros
Merge pull request #134 from scalajp/topic/overview-fix

Fixes language switch for overview layouts
Removing rdiscount from config
corrects a typo in type macros guide
Typo fixes to the progfun statistics article
Merge pull request #137 from xeno-by/master

corrects a typo in type macros guide 
Clarified wording in progfun-stats article
Merge branch 'master' of github.com:scala/scala.github.com
updated the tips & tricks section in the macro guide
adds instructions on getting nightlies of macro paradise
progfun-stats article fix, fixed title of graph, added legend to difficulty graphs
mentions SI-6858
type macro example now uses c.fresh
renames c.fresh to c.freshName
Merge pull request #138 from xeno-by/master

updated the macro guide