Add end-to-end tests:

* `mbed new` with mbed-os imported
* `mbed import` for git, hg and bld examples

Author: screamerbg

circle.yml

@@ -1,10 +1,15 @@
 test:
     override:
         - py.test test
+        - cd ../tests && mbed new new-test
+        - cd ../tests && mbed import https://github.com/ARMmbed/mbed-Client-example-temp git-test
+        - cd ../tests && mbed import https://developer.mbed.org/teams/Morpheus/code/mbed-Client-Morpheus-hg hg-test
+        - cd ../tests && mbed import https://developer.mbed.org/users/samux/code/USBSerial_HelloWorld bld-test
 
 dependencies:
     pre:
         - sudo pip install pytest
         - git config --global user.email "[email protected]"
         - git config --global user.name "Tester"
         - echo -e "[ui]\nusername = Tester <[email protected]>\n" > ~/.hgrc
+        - cd ../ && mkdir tests