Update plugin to add attachments

Plugin has been updated to add attachments from phone or sd card
Correct slashes

Incorrect slashes in file path examples
Merge remote-tracking branch 'upstream/master'

Conflicts:
	BB10-Cordova/EmailSender/plugin/Readme.md
	BB10-Cordova/EmailSender/plugin/plugin.xml
Merge pull request #340 from stefanschielke/master

Update plugin to add attachments