Fix TISTUD-6696 Installing Studio dependencies fails when user has never run sudo before
  - don't just read first line of output from sudo invocation. Read from stream while it's "ready" (won't block) until we see our echo message. Then bail out successfully. Otherwise if we hit point where no output is available and we haven't seen the expected successful echo message, then we kill the process and fail.
Merge pull request #215 from sgtcoolguy/TISTUD-6696

TISTUD-6696 Installing Studio dependencies fails when user has never run sudo before