Added a test to verify user agent prefix can be set correctly.

Explicitly delete node_modules directory after running tests on Windows

Don't fail when generating report.xml on gcc4.4 

Pollset & pollset-set implementation firewalls

Fix fedora20 python distribtest

Fix ruby distribtest on centos6

Fix python distribtest on fedora20 and fedora21.

Revert "Add an implementation firewall against pollset_set"

Add an implementation firewall against pollset_set

Fix PHP pecl install problem on Mac

Have a dedicated server security connector.

Made Alarm's constructor a template for deadline

Change pollset_work signature to allow moving grpc_pollset_worker to implementation