HADOOP-9432 Add support for markdown .md files in site documentation

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1502251 13f79535-47bb-0310-9956-ffa450edef68
initial FS contract as markdown file
Format for line endings
rename file to .md for github to pick up, review and improve text
Merge in Mike Liddell's patch on paths and Matt Farrellee's findings on atomicity of {{rm -rf}} in the current codebase.
Add blocksize rules
HADOOP-9495 Define behaviour of Seekable.seek(), write tests, fix all hadoop implementations for compliance
review and some whitespace
whitespace
whitespace
Add prototype of contract-driven tests for filesystem
quick look through of the source and cleanup, javadocs
remove (swift) test timeouts
block locality feature -false for localfs
work in progress -FS spec
done up to append
compiles
contract done mostly and tests to go with for common and HDFS
changes to the spec -as submitted in patch 9361-002
Local FS to catch -ve seek offsets