Moved slave state API functions to the top of the header.

Review: https://reviews.apache.org/r/16237
Paginated all tasks on the web UI home page.

Angular UI already included a Pagination directive that renders a
Bootstrap-styled pagination list. This configures that directive and
adds paginated task tables to the homepage.

* Pagination displays only if there are more items than can fit on a
  single page
* Default itemsPerPage is 50, which will mean 50 Active Tasks and 50
  Completed Tasks on the home page.
Review: http://reviews.apache.org/r/16331
Fixed a bug that can cause the Master to produce a growing number of
leader detection loops.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/16333
Added timeval retrieval from sysctl.

Review: https://reviews.apache.org/r/16336
Added os::bootId.

This can be used to identify a reboot, should the boot id change.

For OS X and POSIX systems, the boot time in seconds from sysctl and
utmpx (respectively) are used as a good approximation for a unique
boot id.

Review: https://reviews.apache.org/r/16235
Updated the slave to not recover after a reboot.

Review: https://reviews.apache.org/r/16238
Added equality comparator for Option<T> vs T.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/16332
Fixed group to not retry when non-retryable errors are encountered.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/16290
Changed master detector to return Future<Option> instead of
Future<Result>.

Now that local session timeouts are transparent to the clients of the
master detector, they are not supposed to retry anymore. Thus passing
"Result<UPID> previous" back into MasterDetector::detect() is no
longer correct.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/16291
Updated Group to discard futures instead of failing them upon
destruction.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/16345
Added C compiler and flags to python egg build.

The chosen compiler and flags were not propagated to setup.py and
distutils will default to the compiler the particular python was built
with. Selecting a specific compiler for building python eggs is needed
to deal with OS X Mavericks issue.

Review: https://reviews.apache.org/r/16419
Moved control of navbar tabs to MainController

This removes another dependency on jQuery and lets the MainController
control its tabs. `setNavbarActiveTab` was a global function that was
accessing the global DOM, which meant the controllers were editing
things they didn't control.

The MainController now sets the tab based on the path.

We are almost to zero jQuery...

Review: http://reviews.apache.org/r/16395
Paginated tasks on framework pages.

Review: http://reviews.apache.org/r/16396
Fixed an incorrect CHECK in MesosSchedulerDriver::stop that assumes
'process' is always instantiated.

From: Jiang Yan Xu <yan@jxu.me>
Review: https://reviews.apache.org/r/16592
Added freeMemory() to stout.

freeMemory() returns amount of free system memory. Can in
combination with memory() be used to get total used memory.
This allows future finer grained break-downs of used memory
in user memory, kernel buffers/caches and so on.

Review: https://reviews.apache.org/r/16569