Fix where scope in order to use let method in where blocks

- Create ExampleGroup instance for evaluate where block.
- Get parameters from instance.instance_eval
Merge pull request #7 from joker1007/fix_where_scope

Fix where scope, in order to use let method and matcher in where blocks
Remove a not used line
Version 0.0.6
Version 0.0.7

Update rspec version to 2.12.0
rspec: 2.12.0 -> 2.13.0
Merge pull request #10 from sue445/pr/rspec-2.13.0

rspec: 2.12.0 -> 2.13.0
Version 0.0.8