* refactor struct's time to remove unnecessary memory usage

* use AsTimePtr simple code

* fix tests

* fix time compare

* fix template on gpg

* use AddDuration instead of Add

* Take navbar out of column
* Add styles to navbar
* Changed navbar classes
* Remove unneeded !important from index.css
* Remove unneeded !important from _explore.less

- Add site-wide option DEFAULT_KEEP_EMAIL_PRIVATE.
- Add the new option to the install and admin/config pages.
- Add the new option to app.ini in the service section.
- Add the new option to the settings struct.
- Add English text strings to i18n.
- Add field KeepEmailPrivate to user struct.
- Add field KeepEmailPrivate to user form.
- Add option to UI.
- Add using noreply email address if user has "Keep Email Private".
An email address <LowerName>@<NO_REPLY_ADDRESS> is now used in commit
messages (and hopefully all other git log relevant places). The
change relies on the fact that git commands should use
user.NetGitSig().
- Add hiding of email address in UI, if user has set "Keep Email Private".
- Add condition to show email address only on explore/users and user
pages, if user has not set "Keep Email Private".
- Add noreply email in API if set "Keep Email Private".
- Add a new service setting NO_REPLY_ADDRESS. The value of this
setting is used as the domain part for the user's email address in
git log, iff he decides to keep his email address private.
If the user decides to keep his email address private and this
option is not set 'noreply.example.org' is used, which no MTA
should send email to.

Add NO_REPLY_ADDRESS to conf/app.ini.

* UI config to toggle whether user email shows up in Explore Users

* Recommendation made by @tboerger
66a1c59fe7 (r94122732)

* fixed typo, rename ShowUserEmailInExplore to ShowUserEmail

* Fixed typo merged conflict

* Hide email in the user profile page

if you are active ShowUserEmail
ref https://github.com/go-gitea/gitea/pull/336#issuecomment-269843725

* Please replace MustBool() with MustBool(true)

* resolved #296

* Indentation fixed

to reduce code-duplicity

Both are possible on explore and admin panel