[SPARK-4193][BUILD] Disable doclint in Java 8 to prevent from build error.

Author: Takuya UESHIN <ueshin@happy-camper.st>

Closes #3058 from ueshin/issues/SPARK-4193 and squashes the following commits:

e096bb1 [Takuya UESHIN] Add a plugin declaration to pluginManagement.
6762ec2 [Takuya UESHIN] Fix usage of -Xdoclint javadoc option.
fdb280a [Takuya UESHIN] Fix Javadoc errors.
4745f3c [Takuya UESHIN] Merge branch 'master' into issues/SPARK-4193
923e2f0 [Takuya UESHIN] Use doclint option `-missing` instead of `none`.
30d6718 [Takuya UESHIN] Fix Javadoc errors.
b548017 [Takuya UESHIN] Disable doclint in Java 8 to prevent from build error.

(cherry picked from commit e464f0ac2d7210a4bf715478885fe7a8d397fe89)
Signed-off-by: Patrick Wendell <pwendell@gmail.com>