Change format so IDs will be URL friendly formatted

This is an example of an ID:

jGrgxlq/o5IXhHxpiuk9z84DkRI=

URL encoded it is formatted as:

jGrgxlq%2Fo5IXhHxpiuk9z84DkRI= - this can be URL decoded back

However, characters such as + will through URL decoding be removed, so a theoretical image with ID both containing / and + will never be able to be correctly encoded and decoded.

Therefore, I suggest we choose a more URL friendly format of IDs