Add/remove multiple components+targets

[durka]

Same as #986 but for components and targets. After this I don't see any more places to add .multiple(true).

cc #1005

[durka]

Not sure what's going on with multi_host_smoke_test but I can reproduce locally, will figure it out.

[durka]

Another note is that all these loops exit on the first error. If you rustup component add x y and x doesn't exist (or is already installed, see #1009), it won't get to y. I'm not sure whether this is desired behavior.

[brson]

Another note is that all these loops exit on the first error. If you rustup component add x y and x doesn't exist (or is already installed, see #1009), it won't get to y. I'm not sure whether this is desired behavior.

Seems ok for now when there are no dependencies between components that need to be maintained.

[durka]

Should be fixed now. Not really sure what I'm doing in the mock manifest code.

[Diggsey]

@bors r+ Thanks!

[bors]

📌 Commit cea6164 has been approved by Diggsey

[bors]

⌛ Testing commit cea6164 with merge af52e4d...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: Diggsey
Pushing af52e4d to master...