Addition/improvements to utils.py

https://github.com/subuser-security/subuser/issues/61

improved subprocessCheckedCall: argument: addToErrorInfo
e.g.code

```
subuserlib.utils.subprocessCheckedCall(["docker", "-d"], "ATTENTION: Special added info bla bla")
```
output

```
[/var/lib/docker|1038baec] +job initserver()
[/var/lib/docker|1038baec.initserver()] Creating server
mkdir /var/lib/docker/containers: permission denied[/var/lib/docker|1038baec] -job initserver() = ERR (1)
2014/02/21 09:53:09 initserver: mkdir /var/lib/docker/containers: permission denied
Command <docker -d> failed:
  ERROR: Command '['docker', '-d']' returned non-zero exit status 1
    ATTENTION: Special added info bla bla
workerm@notebook:~$ 


```



https://github.com/subuser-security/subuser/issues/8
ADDED: utils.getUserCommandLine

this will help to solve some of #8

used code for install

```
commandOptionList = ['--from-cache']
userProgramList, userOptionList = subuserlib.utils.getUserCommandLine(sys.argv[1:], commandOptionList)
print('userProgramList: ', userProgramList)
print('userOptionList: ', userOptionList)
```


outputs: multiple programs called with option

```
workerm@notebook:~$ subuser install vim firefox --from-cache
('userProgramList: ', ['vim', 'firefox'])
('userOptionList: ', ['--from-cache'])
workerm@notebook:~$ 

```

option are not confined anymore to any specific order in the commandline arguments

```
workerm@notebook:~$ subuser install --from-cache vim firefox
('userProgramList: ', ['vim', 'firefox'])
('userOptionList: ', ['--from-cache'])
workerm@notebook:~$ 
```

wrong program

```
subuser install libx11 --from-cache vim firefox  wrongprogram
<wrongprogram> not an available subuser-program

Available programs are:
   docker-in-docker
   elm-get-git-dev
   elm-git-dev
   emacs
   firefox
   firefox-flash
   firefox-java
   firefox_libx11_libubuntu_precise
   git
   irssi
   libelm-platform-git-dev
   libhaskell-platform
   libreoffice
   libubuntu_precise
   libx11
   libx11_libubuntu_precise
   skype
   vim
   xterm

workerm@notebook:~$ 
```
Merge branch 'patch-5' of https://github.com/peter1000/subuser
Rename getUserCommandLien to parseCommandLineArgs, generalize function by removing program availability checking code.