[MERGE #3289 @agarwal-sandeep] Allow runtests.cmd to be executed from any directory
[MERGE #3289 @agarwal-sandeep] Allow runtests.cmd to be executed from any directory

Merge pull request #3289 from agarwal-sandeep:runtestsalldir

No need to be in tests directory explicitly.

mrkmarron/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,mrkmarron/ChakraCore,Microsoft/ChakraCore,Microsoft/ChakraCore,Microsoft/ChakraCore,Microsoft/ChakraCore