Updated media uploading alert text.
When uploading media, users are no longer...

...allowed to leave the post until the media upload is complete.
Merge branch 'release/4.6' of github.com:wordpress-mobile/WordPress-iOS into issue/editor-344-media-upload-blocker

# By Sérgio Estêvão
# Via Sérgio Estêvão
* 'release/4.6' of github.com:wordpress-mobile/WordPress-iOS:
  Make WordPressAPI pod point to a proper tag.
Updated to the most current 0.2.3 editor which contains a bugfix for image replacement
Merge pull request #2725 from wordpress-mobile/issue/editor-344-media-upload-blocker

Issue/editor 344 media upload blocker