added angular-piwik service file, implemented  getStatistic method
added test, bugs fixed
added transformRequest, refactoring name of service to Piwik
added DataTransformer service + test
 testing data transformer
refactoring piwik service
fixed comment
refactoring DataTransformer service + tests fixed
refactoring test
refactoring
changed files names
Merge pull request #6 from anitawlosek/feature/5-service

Feature/5 service