added Buildkite pipeline and integration tests

This pipeline contains the tests that are currently run for
kvm-ioctls. The pipeline also has a step that runs the coverage
test defined in integration_tests/test_coverage.py.

The purpose of this pipeline is to be used by all rust-vmm
repositories to ensure we keep the same quality bar for all crates.

Signed-off-by: Andreea Florescu <fandree@amazon.com>

integration_tests/conftest.py

@@ -0,0 +1,30 @@
+# Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+import pytest
+
+
+PROFILE_CI="ci"
+PROFILE_DEVEL="devel"
+
+
+def pytest_addoption(parser):
+    parser.addoption(
+        "--profile",
+        default=PROFILE_CI,
+        choices=[PROFILE_CI, PROFILE_DEVEL],
+        help="Profile for running the test: {} or {}".format(
+            PROFILE_CI,
+            PROFILE_DEVEL
+        )
+    )
+
+
+@pytest.fixture
+def profile(request):
+    return request.config.getoption("--profile")
+
+
+# This is used for defining global variables in pytest.
+def pytest_configure():
+    pytest.profile_ci = PROFILE_CI
+    pytest.profile_devel = PROFILE_DEVEL