Fix upload profile photo

Was writing feature descriptions for "Speaker edits their profile" and ran across this. The user `photo_path` property was not being set even though the image uploads were working perfectly. Fixing that highlighted the fact that because `speaker_photo` is sent on every update request, there was required checking to make sure that the `photo_path` wasn't unintentionally nulled-out just because they didn't select another image.

In addition, 7640635 augments the error reporting on the page such that:

- If invalid data is entered, appropriate error messages are still shown to the user
- When legit data is entered **and data has changed**, a success message appears
- **When the "update profile" button is clicked without changing anything, a success message appears even though no data has changed.** Previously, an error message was shown stating that "We were unable to update your information. Please try again.".  

Please let me know if you want the error message removal reverted.  If so, I would suggest changing the error message to something like "Ooops silly... you didn't change anything" under an "info"-class alert.