conan-io#3649 Update CI templates (conan-io#3651)

* conan-io#3649 Update CI templates

- CONAN_REFERENCE is no longer required
- Add GCC 8 on default CI template list
- Add Clang 5, 6 on default CI template list
- Update unit test to avoid CONAN_REFERENCE

Signed-off-by: Uilian Ries <uilianries@gmail.com>

* conan-io#3649 Update Conan Package Tools template

- User new CPT import

Signed-off-by: Uilian Ries <uilianries@gmail.com>

* conan-io#3649 Revert Conan reference in new CI

- Conan reference is mandatory when the recipe does not contain
  name and version.

Signed-off-by: Uilian Ries <uilianries@gmail.com>

* conan-io#3649 Update appveyor template to run python3

- Replace Python27 by Python37. Both Python arch and version are no
longer required.
- Update Travis using Xenial as base image

Signed-off-by: Uilian Ries <uilianries@gmail.com>

* conan-io#3649 Update docker image names

Signed-off-by: Uilian Ries <uilianries@gmail.com>

* conan-io#3649 Update unit test for new CI

Signed-off-by: Uilian Ries <uilianries@gmail.com>

conans/client/cmd/new_ci.py

@@ -10,6 +10,7 @@
      {upload}
 linux: &linux
    os: linux
+   dist: xenial
    sudo: required
    language: python
    python: "3.6"
@@ -48,7 +49,7 @@
         env: CONAN_APPLE_CLANG_VERSIONS={version}
 """
 
-build_py = """from conan.packager import ConanMultiPackager
+build_py = """from cpt.packager import ConanMultiPackager
 
 
 if __name__ == "__main__":
@@ -103,9 +104,7 @@
 appveyor = r"""build: false
 
 environment:
-    PYTHON: "C:\\Python27"
-    PYTHON_VERSION: "2.7.8"
-    PYTHON_ARCH: "32"
+    PYTHON: "C:\\Python37"
 
     CONAN_REFERENCE: "{name}/{version}"
     CONAN_USERNAME: "{user}"

conans/test/command/new_test.py

@@ -135,6 +135,7 @@ def new_ci_test(self):
         self.assertIn('CONAN_REFERENCE: "MyPackage/1.3"', appveyor)
         self.assertIn('CONAN_USERNAME: "myuser"', appveyor)
         self.assertIn('CONAN_CHANNEL: "testing"', appveyor)
+        self.assertIn(r'PYTHON: "C:\\Python37"', appveyor)
         self.assertIn('CONAN_VISUAL_VERSIONS: 12', appveyor)
         self.assertIn('CONAN_VISUAL_VERSIONS: 14', appveyor)
         self.assertIn('CONAN_VISUAL_VERSIONS: 15', appveyor)