Added Server task
Addded simple exception module
Making sure Sinatra is loadded
Added A Sinatra app to serve the files in preview mode
Added sinatra to runtime dependency
Inherit from Sinatra::Bae intead of Sinatra::Application
resuire base sinatra class
refactoring
fix server command
refactor server
refactoring
refactoring
moved to lib  dir
moved to lib
moved out of layouts folder
moved to blogdown direcory
refactoring