Support of Variables in EXPORTED_PATHS and TOOL_HOME + bug fixes (JENKINS-14515 and JENKINS-17844)

Hello,

I have added support of variables in definitions of Custom Tools. So, now it is possible to specify paths according to job parameters and slave’s configuration. For example, this feature can be used in order to specify paths to shared directories with tools, which can be mounted to different locations.

Changes summary:
• Added support of Properties in EXPORTED_PATHS and TOOL_HOME (supports job’s environment and slave’s properties, but doesn’t work with EnvInject)
• Fixed bug in the validation of exported paths (now code works well for both relative and absolute paths)
• Fixed bug with delimiters in EXPORTED_PATHS in case of different slave/master’s operating systems

![customtoolspublic](https://f.cloud.github.com/assets/3000480/639383/9870a28a-d2d1-11e2-94e9-d49f5d5c530b.png)

Best regards,
Oleg Nenashev
R&D Engineer, Synopsys Inc.
www.synopsys.com

Affected issues: 
* https://issues.jenkins-ci.org/browse/JENKINS-14515
* https://issues.jenkins-ci.org/browse/JENKINS-17844