FS-7593 --resolve  add locking keyed on device name around any database updates adding/removing the device

Ephemeral ECDH (ECDHE) was supported already. This patch adds Ephemeral
DH (DHE). To enable it, add DH parameters into the private-key file of
your server (agent.pem). For example via:
openssl dhparam -out dh.pem 2048

FS-7561 #resolve

FS-7513 add video-auto-floor-msec param to control how long a member must have the audio floor before also taking the video floor %NEEDS_DOC

little more tolerant of big timing errors between the symbols at the far end,
and as they are received by us.

* commit 'b641ab6d': (629 commits)
  bump
  FS-7519: CID:1294454 fix leak
  CID:1301145,1301144: Bit shift bounds checking
  CID 1216601 Fix a possible memory leak in mod_basic
  FS-7519 mod_av cleanup and refactor to work on higher resolution
  FS-7513 refactor
  FS-7500 FS-7499 refactoring while battling chrome
  FS-7585: add rtmp video support
  FS-7585: spaces to tabs and clean up trilling spaces
  FS-7519: reverting part of f85a86e64d3ebcd34d63bc6239694e5a524760a1
  FS-7519: fix build issue with clang-3.5
  FS-7500: start media thread one answer/pre_answer
  FS-7519: fix typo
  FS-7499 FS-7500 mods for interop against latest chrome builds
  FS-7500 just send refresh and not full reset on uuid_video_refresh
  FS-7513 mods to bandwidth sizing and remove flush calls
  FS-7519: auto set some values on avformat recording
  FS-7519: [mod_av] fix modules.conf
  FS-7519: merge mod_avcodec and mod_avformat into mod_av
  FS-7553 reduce opencv library requirement to 2.4.5 to allow centos 7
  ...