Add basic support of PJAX request
Code cleaning :
- corrected many typos and spelling errors
- renamed the namespace to KrtekBase
- renamed the 'list' action to 'listing' to avoid problems with the reserved keyword list
- cleaned a lot of code to avoid warnings / notices / errors
- use the Message class only if the package is loaded
- include classes from fuel core through 'use' or at least fully qualified class names
- cleaned phpdoc