Fix monit flakiness on go-agent

Don't close the reader before reading from it
Don't reuse http request on subsequent retry attempts

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Add go-agent build script for linux-amd64

For this to work go needs to be build from source

Signed-off-by: Maria Shaldibina <mariash@pivotallabs.com>
Wait for monit to be reloaded

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
Increase canary update time for vsphere, vcloud bats

Go agent sends monit start/stop faster and fails if previous action is
still penging

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>