Updated Vagrantfile for bin/run-tests-vagrant script

First, I cleaned and updated the `Vagrantfile`. I verified it with both `aws` and `virtualbox`.

Second, I added a `bin/run-tests-vagrant` script. I envision a Jenkins build script with:

 > Environment Variables:
 > 
 >  * `AWS_KEYPAIR_NAME` - I created a new `jenkins-slave-20140218a` key and added it to `eu-west-1` and Jenkins' configuration file plugin
 >  * `AWS_PRIVATE_KEY_PATH` -  auto-generated by the configuration file plugin
 >  * `AWS_VAGRANT_USE_IAM=true` - for vagrant creating the instance
 >  * `AWS_VAGRANT_IAM_PROFILE_NAME` - tests require the `cloudformation:ValidateTemplate` permission
 > 
 > Script:
 > 
 >     chmod 700 $AWS_PRIVATE_KEY_PATH
 >     ./bin/run-tests-vagrant aws destroy
 > 

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This is pull request is related to the build issues of #303, #300