Merge pull request #186 from yusuke/master

fixes #185 - implement DocumentValidator initialization process in a ServletContextListener instead of a Servlet
fix: set maven-compiler with source level 1.6 to build
Merge pull request #187 from ainoya/fix-build-server-failure-ubuntu

[redpen-server]fix: set maven-compiler with source level 1.6 to build
Add Confiugration.Builder class and the sample tests
Make ValidatorConfiguration.getAttribute return the ValidatorConfiguration object in order to simplify the builder process of Configuration.

- changed ValidatorConfiguration.getAttribute signigure
- added a test with addAttribute method
Apply Configuraiton.Builder into ConfigurationLoader
Apply Configuration.Builder
Merge pull request #188 from takahi-i/config-builder

Configuration Builder
Remove configuration strings replacing them into Configuration.Builder
Extract override method in CharacterTableLoader
Add character setting methods to Configuration.Builder
Apply Configuration.Builder' character setting method removing config strings
Add ConfigurationLoader.loadNewConfionMethod (Not finished yet)
Implement loading validator config
Implement loading character config
Implement handlings of corner cases of and add the tests
Apply new config load method as a testing
Remove ConfigurationLoader.laodLongiuration and ValidatorConfigurationLoader
Rename ConfigurationLoader.loadNewConfiguration into loadConfiguaration
Port test of CharacterTableLoader to ConfigurationLoaderTest