Remove waf and updated README.md

Removed the waf-based build tool from this repo as the tool is now
located in a different repo (bde-oss-tools on devgit, and bde-tools on
github). Added a new section to README.md containing basic build instructions.
Remove "Looking for BSL" from README.md
Update per review.
Update basic build instructions.
Correct typo.
[APPROVAL] remove-waf-drqs-53466599 to master