[AESH-261]
operators should not be parsed inside double or single quotes
[AESH-263]
added pid to ConsoleOperation and CommandInvocation
[AESH-263]
added foreground and background status for processes
[AESH-263]
command should not be able to put themselves in the background and foreground
AESH-264
[AESH-260] Not load System.getenv() on forge.
[AESH-265]
added error stream
[AESH-263]
commands can now execute other commands by pushing to the input stream
Merge pull request #89 from danielsoro/AESH-260

[AESH-260] Not load System.getenv() on forge.
Merge pull request #88 from eprogramming/AESH-264

AESH-264
codestyle + cleanups