When running restcli with multiple .http files as input the exit code returned is success in the event that a test failed

[alexbanica]

Steps to reproduce:

1. Create a http file with a failing test (failing-test.http)
2. Create a http file with a successful test (success-test.http)
3. Excecute java -jar restcli.jar failing-test.http success-test.http or java -jar restcli.jar /*.http

Results:

• if the last executed http file is successful but the first ones failed, restcli exit code is 0

Expected:

• If any of the .http files tests failed no matter in what order, restcli should exit with code 1.

Proposed PR: #106