feature-output branch started

The purpose of this branch is to change the way you write classes which
output some data to the response
Wrote stubs for other output formats
Removed former classes
Moved PlainTextResponseFilter to PlainTextOutput
Merged services, filters and outputs into a single thing
Fixed AdminSite
Added TCPDFOutput
Changed output flusher
feature-input branch started

Change request filters into input objects
Renamed ExcelOutput to PHPExcelOutput
Added $input variable in Server's scope
Using setProvider to register outputs
Added RedirectionOutput
Merge remote-tracking branch 'origin/feature-output'
Merge remote-tracking branch 'origin/feature-input'