inline image support

[adael]

Hello I have added support to show inline images in the outgoing email (the images are shown alongside the text). IE: when you modify an issue and you paste an image using the plugin redmine_image_clipboard_paste.

I found it very useful so I wanted yo share.

Regards,

[jfqd]

Thank you for taking the time to create this pull request! I am sorry that I currently do not have the time to review it.

Would it be possible for you to fix the tests?

[adael]

I would if I could figure out how, but it seems to be some kind of configuration error in Travis file.
It isn't because of the tests files themselves but the installer when executes bundle install to install Redmine package dependencies.

Here -> bundle install --jobs=3 --retry=3

I'm really wanted to write new tests for this feature, but I'm afraid I have no time either. Perhaps in another pull.

[vilppuvuorinen]

The Travis build has not been modified in a while now. It certainly could use a bit upgrading. Some Ruby versions in the matrix are pretty much ancient by now and later Redmine versions are not tested at all.

Fixing those could be a subject for another pull request. I feel like this is partially my fault because I initially introduced them. I'll have to see if I can conjure up some time to figure them out again.