Silence RSpec's deprecation warnings.

- DEPRECATION: mock is deprecated. Use double instead.
- WARNING: let declaration `builder_engines` accessed in a `before(:all)` hook

Checked against RSpec 2.14.8.
Update dependencies
Bump version to 1.0.10
Fixed RSolr::Error to_s
Merge pull request #78 from PofMagicfingers/master

Fixed RSolr::Error to_s
Merge pull request #75 from blackwinter/rspec-deprecation

Silence RSpec's deprecation warnings.