Fix Solutions i18n issues

@chrisndodge @muhhshoaib @martynjames : this fixes some i18n problems introduced in 
https://github.com/edx/edx-platform/commit/2cc0433833bee4ccfb4955bfdbbff0edc363920a

We need to be really careful with i18n, it causes me a lot of headache when stuff is improperly marked up for i18n, because I have to drop everything, deal with translators, and make PRs to fix strings. Please read through https://github.com/edx/edx-platform/blob/master/docs/en_us/developers/source/i18n.rst and ask me if you have any questions.
Yep, same question I had asked Chris above. Since these instructions were only partially translated in `lms/templates/emails/account_creation_and_enroll_emailMessage.txt` I wasn't sure if they were actually intended to be translated or not. The reason I pinged @chrisndodge was to ask if these strings should actually be translated or not. They are really confusing to translators because of the "[[ ]]" variables, so if they need to be translated I need to add a ton of translators comments.