Support RSpec 3

The way to access a current example object has been changed in RSpec 3.

* http://myronmars.to/n/dev-blog/2013/07/the-plan-for-rspec-3#core_dsl_methods_will_yield_the_example
* https://github.com/rspec/rspec-core/blob/7d6d2ca/lib/rspec/core/example_group.rb#L513-L527
Merge pull request #30 from yujinakayama/support-rspec-3

Support RSpec 3
Bump up version
support sudo-options
add sudo_options to configuration
add sudo-options spec
Merge pull request #31 from linyows/sudo_options

sudoにオプションを指定出来るように
Bump up version
add copy for configspec
review
Merge pull request #32 from sonots/append

add append command
Bump up version
ssh copy_file
Merge pull request #33 from sonots/ssh_copy_file

ssh copy_file
Bump up version
Avoid using grep and awk during OS detection
Merge pull request #34 from hanazuki/detectos-debian

Avoid using grep and awk during OS detection
Bump up version
Implement Docker backend
Merge pull request #35 from hanazuki/docker-backend

Implement Docker backend