Add comments and improve readability of test code
Fix #105 division by zero error if elapsed time is zero
Merge branch 'issue/105' of pull request #106

This pull request fixes the bug file transfer eventually fails due to division by zero error. Also refactors the test of progress monitor.
Upgrade to Gradle 2.0-rc-1
Remove code to exclude older JSch bundled with Gradle 1.x
Upgrade spock dependencies for Groovy 2.x
Upgrade to Gradle 2.0-rc-2