Update the protocol version to 7
Refactor how activity timeouts are adjusted

* remove ping requests
* instead of pinging, manager assistants adjust the timeouts on connections
* connection manager is the only one that performs activity checks
* update specs
Use handshake-specific activity timeouts
Log the number of Pusher instances to the timeline
Convert handshake activity_timeout to miliseconds
Always send all session details with stats
Filter undefined parameter in timeline senders
Separate encrypted/non-encrypted transport caches
remove global variable
Merge branch 'log_number_of_instances' into r2.1.5
Merge branch 'use_server_timeouts' into r2.1.5
Merge branch 'resubmit_stats_details' into r2.1.5
Merge branch 'cache_transports_with_encryption' into r2.1.5
Merge remote-tracking branch 'abaran/fix-global-variables' into r2.1.5
Update failing integration tests
Merge branch 'use_server_timeouts' into r2.1.5
Fix the Flash check sometimes failing on Firefox
Bump version to 2.1.5
Update the changelog for version 2.1.5
Update distribution files to version 2.1.5