[SPARK-2857] Correct properties to set Master / Worker ports

`master.ui.port` and `worker.ui.port` were never picked up by SparkConf, simply because they are not prefixed with "spark." Unfortunately, this is also currently the documented way of setting these values.

Author: Andrew Or <andrewor14@gmail.com>

Closes #1779 from andrewor14/master-worker-port and squashes the following commits:

8475e95 [Andrew Or] Update docs to reflect changes in configs
4db3d5d [Andrew Or] Stop using configs that don't actually work
(cherry picked from commit a646a365e3beb8d0cd7e492e625ce68ee9439a07)

Signed-off-by: Patrick Wendell <pwendell@gmail.com>
[SPARK-1779] Throw an exception if memory fractions are not between 0 and 1

Author: wangfei <scnbwf@yeah.net>
Author: wangfei <wangfei1@huawei.com>

Closes #714 from scwf/memoryFraction and squashes the following commits:

6e385b9 [wangfei] Update SparkConf.scala
da6ee59 [wangfei] add configs
829a195 [wangfei] add indent
717c0ca [wangfei] updated to make more concise
fc45476 [wangfei] validate memoryfraction in sparkconf
2e79b3d [wangfei] && => ||
43621bd [wangfei] && => ||
cf38bcf [wangfei] throw IllegalArgumentException
14d18ac [wangfei] throw IllegalArgumentException
dff1f0f [wangfei] Update BlockManager.scala
764965f [wangfei] Update ExternalAppendOnlyMap.scala
a59d76b [wangfei] Throw exception when memoryFracton is out of range
7b899c2 [wangfei] 【SPARK-1779】