Add an Applicative instance for our Result type
Add an Applicative instance for our Result type

This will allow us to run generic computations in an Applicative
context, if a monadic one is not needed (or not applicable due to
class constraints).

Signed-off-by: Iustin Pop <acf83a5274f31a43af6b914614365999469c1a31@google.com>
Reviewed-by: Agata Murawska <4c8886dbe342c6966e25105100cfee09458faa93@google.com>

bitemyapp/ganeti,dimara/ganeti,mbakke/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,mbakke/ganeti,andir/ganeti,yiannist/ganeti,andir/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,grnet/snf-ganeti,yiannist/ganeti,onponomarev/ganeti,apyrgio/ganeti,apyrgio/snf-ganeti,leshchevds/ganeti,yiannist/ganeti,grnet/snf-ganeti,dimara/ganeti,ganeti/ganeti,andir/ganeti,ganeti/ganeti,mbakke/ganeti,bitemyapp/ganeti,apyrgio/ganeti,leshchevds/ganeti,leshchevds/ganeti,ganeti-github-testing/ganeti-test-1