Adding support for environment variable substitution in command
execution. This allows for the use of ${Env.*} variables to be used by
commands and their parameters that will be parsed before being executed
by the OS.

The environment variables are composited in order of system, then
environment context, then processing specified, which each layering on
top of the previous. e.g. Variable Test1 in all three scopes would
resolve to the one specified by the command.

Having this functionality alleviates the need to create mini batch/shell
files that forward variables as parameters to executables or for
constructing the relative path to the executables sync as part of
materials.
Merge remote-tracking branch 'upstream/master'
Initial commit
Delete README.md
Merge branch 'master' of https://github.com/turbine-rpowers/gocd-add-agent-sandbox-config

Conflicts:
	README.md
Merge remote-tracking branch 'origin/master'

Conflicts:
	README.md
Merge remote-tracking branch 'upstream/master'
Fixing readme.
Added two new environment variables used to configure the server and
agent to allow more control over where pipeline directories are created.

The first environment variable, GO_PIPELINE_WORKING_DIR, is used by the
server to change the path where pipelines are create. If empty,
pipelines are created in the sandbox directory on the agent.

The second environment variable, GO_AGENT_SANDBOX_DIR, is used by the
agents to determine where the pipelines folder will be located.

Using these together you can set the GO_PIPELINE_WORKING_DIR to nothing
and then the GO_AGENT_SANDBOX_DIR to a scratch disk such that you
dedicate a drive for your go work.
Merge remote-tracking branch 'vss/master' into feature-environment-variable-substitution-support
Merge remote-tracking branch 'cas/master' into feature-custom-agent-sandbox-support
Merge pull request #1 from Turbine-GamePlatform/feature-environment-variable-substitution-support

Feature environment variable substitution support
Merge pull request #2 from Turbine-GamePlatform/feature-custom-agent-sandbox-support

Feature custom agent sandbox support
Merge pull request #3 from Turbine-GamePlatform/dev

gocd merge 2014-05-27