Remove 'app_units' component from tree

Part of #8012
servo · bors-servo · Oct 19, 2015 · Oct 14, 2015 · Oct 14, 2015 · 98c621ed43b69191a4ad0cf0005aa7f14587f3ce
commit 98c621ed43b69191a4ad0cf0005aa7f14587f3ce
diff --git a/components/app_units/Cargo.toml b/components/app_units/Cargo.toml
diff --git a/components/app_units/src/app_unit.rs b/components/app_units/src/app_unit.rs
diff --git a/components/app_units/src/lib.rs b/components/app_units/src/lib.rs