一些小的笔误，不通顺语句的修改
Merge pull request #22 from lynus/master

Fix some issues of doc.
Merge branch 'master' into dev
Update version to 20140510+
Update pdf according to 8ce479635f6b66e6d340430e9dc4badf7f765198
Thanks Linyu Zhu <lynuszhu@gmail.com>'s work.