It persist temporary personal snippets under
user/:id namespaces temporarily while creating
a upload record to track it. If an user gets removed
while it's still a tmp upload, it also gets removed.
If the tmp upload is sent, the upload gets moved to
personal_snippets/:id as before. The upload record
also gets updated to the new model type as well.

This commit, introduced in https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/23812,
fixes a problem creating a displaying image diff notes when the image
is stored in LFS. The main problem was that `Gitlab::Diff::File` was
returning an invalid valid in `text?` for this kind of files.

It also fixes a rendering problem with other LFS files, like text
ones. They LFS pointer shouldn't be shown when LFS is enabled
for the project, but they were.

Partially addresses #47424.

Rearranged datetime created line

Added `avatar_class` option to `link_to_member` so it can be hidden

Made snippet title font heavier

Added file title  bar

Hidden unneeded info from xs screens

Added visibility icon

Reveal file-actions on xs screens

Added comments icon to snippets list items

Refactored no-comments declaration into framework stylesheet

Final touch ups

Fixed snippets_spec

This was removed from the interface in
https://github.com/gitlabhq/gitlabhq/pull/6027 but its implementation
lingered around for two years.

Make the following changes to deal with new behavior in Rails 4.1.2:

* Use nested resources to avoid slashes in arguments to path helpers.