Update epub_library.json

Add the second author of 'page-blanche' (see opf file).
Update toc.ncx (Page-Blanche)

Fix one EpubCheck 3.0.1 error (dtb:uid incorrect).
Update package.opf (Page-Blanche)

Fix one EpubCheck 3.0.1 error (meta cover incorrect).
Update toc.ncx

Remove the Doctype (EpubCheck 3.0.1 error).
Update messages.json (de)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Update messages.json (fr)

* typos
* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: new text translated from the english version
Update messages.json (id)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Update messages.json (it)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Update messages.json (ja)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Update messages.json (ko)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Update messages.json (pt_BR)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Update messages.json (zh_CN)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Update messages.json (zh_TW)

* i18n_add_items: Delete <br/>
* i18n_html_readium_tm_a_project: change the github repository reference
Merge pull request #59 from vincent-gros/develop

Minor changes (i18n and epub-content)
Merge remote-tracking branch 'origin/develop' into feature/prevNextPage