support initialize local volume mapping in hyper run

[bergwolf]

This is based on top of #117 and adds local volume initialisation support.
User can use hyper run -v /local/dir:/container/dir to map a local file or directory to container.

NOTE: this will be broken with the incoming port mapping support. That is the reason I pushed this local volume support PR separate from original #117

Test results:

[lear@hyper-private]$zenlayer run -d -v /home/bergwolf/workplace/golang/src/github.com/bergwolf:/data busybox
0afc562a68be2a0cc8c5c9f18cfce3472cb8f7581d4cc33360611662b53b1f55
[lear@hyper-private]$zenlayer exec 0afc562a68be2a0cc8c5c9f18cfce3472cb8f7581d4cc33360611662b53b1f55 df
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda              10190100     38080   9611348   0% /
devtmpfs                252088         0    252088   0% /dev
tmpfs                   253560         0    253560   0% /dev/shm
/dev/sdb              10190100     37272   9612156   0% /data
share_dir                 1024         4      1020   0% /etc/hosts
[lear@hyper-private]$zenlayer exec 0afc562a68be2a0cc8c5c9f18cfce3472cb8f7581d4cc33360611662b53b1f55 ls -LR /data
/data:
data
goftp
main.go

/data/data:
main.go

/data/goftp:
LICENSE
README.md
doc.go
ftp.go
ftp_test.go
upload.go

[laijs]

sync.WaitGroup seems better.

[laijs]

chan error can pass error, but sync.WaitGroup can't.

[bergwolf]

WaitGroup has to wait for all ExecCmd goroutines to stop before checking results, while current implementation can check for results as it goes and returns failure as soon as any command fails.

[bergwolf]

chan error has to stay even if execCount is changed to sync.WaitGroup.

[laijs]

in the code before this patch, the execs are running parallel.
only the requests are sent in order. it is more efficient to send the requests parallel, but the changelog is confusing.

[bergwolf]

It is more about waiting in parallel rather than issuing requests in parallel. I'll fix up the changelog.

[bergwolf]

updated to address @laijs's comments and rebase to latest master.