[webapp] re-enable adding new providers

Signed-off-by: Juha Kallioinen <juha.kallioinen@jolla.com>
[providers] do not display provider url in parentheses

Signed-off-by: Juha Kallioinen <juha.kallioinen@jolla.com>
[process] enable canceling started processes

Signed-off-by: Juha Kallioinen <juha.kallioinen@jolla.com>