[ci] Added .travis.yml.

This is currently pretty basic, just builds b2 and runs the tests.
[ci] Added support for testing on Linux, OS X.

Note that multi-os testing is not currently enabled on travis-ci.  This
will ensure it runs on more than just the Linux platform when it is
available.
[doc] Remove whitespace and end-of-line.
[doc] Convert .html to .rst.

This makes the information readable directly from GitHub or in a text
editor.  This removes the .html files and replaces them with a Makefile
to generate the same .html files from .rst source.
[doc] Convert .txt to .rst.

This will make these files more readable on GitHub directly.
[doc] Moved hacking document to root.