Update changelog for #154 and #186
#154: Update documentation to include API docs and code coverage report
Refactoring: Extends Endnotes from Footnotes & Heder from Footer
Word2007 Writer: Refactor writer parts using composite pattern
Improved Test Unit for Image Style in line with additions of #217
Merge pull request #226 from basjan/image-test-unit

Thanks @basjan.
Merge remote-tracking branch 'upstream/develop' into develop
Refactor: Composite Word2007 & ODText writer parts
Enable code coverage in Scrutinizer
Fix Travis test and update Scrutinizer config
Show code quality and test code coverage badge on README
#186 : Add badges for license & stable version