pFilename is required parameter for save
Merge branch 'master' of https://github.com/PHPOffice/PHPPowerPoint
Update interface
Merge pull request #19 from sapfeer0k/master

pFilename is required parameter for save
IMPROVED : Travis CI Cleaning
Merge branch 'master' into develop

Conflicts:
	CHANGELOG.md
	Classes/PHPPowerPoint/Writer/IWriter.php
	Classes/PHPPowerPoint/Writer/ODPresentation.php
	Classes/PHPPowerPoint/Writer/PowerPoint2007.php
	Classes/PHPPowerPoint/Writer/Serialized.php