update specs:

* create spec for Lrun::Runner
* slightly update spec for Lrun
cleaning

* replace "raise X.new(m)" with "raise X, m"
* fix some mistyped type names
* fix some incorrect indent
reject empty command in Lrun.run
spec: fix :if clause

* nested :if overwrites parent :if, remove them
README: 'example codes' -> 'examples'
add aliases for rake tasks
create a rubygem for this project