Initial commit for the official OP-TEE documentation

This initial commit brings in all existing documentation found across
various gits making up the documentation for the OP-TEE project. So in
summary what this includes and what has been done is:

- Import all old documentation (optee_os, optee_client, optee_test and
  so on).
- Convert everything from markdown (*.md) to reStructuredText (*.rst).
- Add a couple of new pages (optee_docs, disclosure policy to name a
  few).
- Add Sphinx configuration.
- Add Travis configuration to enable automatic testing of future
  documentation patches.
- Finally, a general clean-up and verification of content,
  links as well as verification of build instructions etc has also been
  done.
diff --git a/.travis.yml b/.travis.yml
new file mode 100644
index 0000000..9b7fbf3
--- /dev/null
+++ b/.travis.yml
@@ -0,0 +1,19 @@
+sudo: false
+
+language: python
+
+python:
+        - "2.7"
+        - "3.6"
+
+before_install:
+  - sudo apt-get update
+  - sudo apt-get install -y graphviz
+
+install: pip install sphinx sphinx_rtd_theme
+
+notifications:
+  - email: false
+
+script:
+  - make html