(SERVER-160) add known issue to documentation

Copy the known issue about /tmp mounted as 'noexec' from the PE documentation.
(SERVER-160) update docs on known issues
(SERVER-160) fix typo
(SERVER-160) additional explanation on known issue
(MAINT) Revert back to Beaker 1.17.X
Merge pull request #318 from waynr/maint

(MAINT) Revert back to Beaker 1.17.X
Merge pull request #311 from KevinCorcoran/SERVER-160

(SERVER-160) add known issue to documentation