ICE restart explanation added, et al

https://github.com/openpeer/ortc/issues/59

-Fixes for error handling, as described in Issue 75
https://github.com/openpeer/ortc/issues/75

- Fixes for miscellaneous NITs, as described in Issue 76
https://github.com/openpeer/ortc/issues/76

- Enable retrieval of the SSRC to be used by RTCP, as described in Issue 77
https://github.com/openpeer/ortc/issues/77

- Support for retrieval of audio and video capabilities, as described in Issue 81
https://github.com/openpeer/ortc/issues/81

- getStats interface updated, as described in Issue 82
https://github.com/openpeer/ortc/issues/82

- Partially addressed SVC issues described in Issue 83
https://github.com/openpeer/ortc/issues/83

- Partially addressed statistics update issues described in Issue 85
https://github.com/openpeer/ortc/issues/85