If users are added to gogs due a reverse proxy automatically, their password is
set to their initial username. If their username is shorter than 6 characters,
they can never set a password. But since this password is required for some
operations (e.g. repository deletion), they could not use all features of gogs
until now.

- modules/middleware/context.go: add HandleAPI method

- routers/user: little code format
- conf/locale: update French locale

The normal go get protocol is to show the go-import meta tag when ?go-get=1 is appended to the url. This commit implements that behaviour and cleans the go-get option from the repository settings page.

- routers: use new binding convention to simplify code
- templates: able to set HTTP port number in install page

All basics are implemented. Missing are the right (localized) strings
and the page markup could have a look at by a frontend guy.

- POST /user/repos
- POST /org/:org/repos

Removed trailing whitespaces with

```sh
for file in `grep -r " $" * | cut -d : -f 1 | sort | uniq | grep -v " "`; do sed -i 's/[ \t]*$//' $file; done
```

and some handwork.