Introduce CTS_SRC_ROOT classpath variable for cts-tradefed.

Use a Eclipse classpath variable to locate cts-tradefed dependent jars,
instead of linking them as separate Eclipse projects. This change
will make it easier to switch between cts branches under development.

Change-Id: I6f4b5e36aba90f1c2bc9f346ae84cfa2c5cae481
2 files changed