Revert of Convert internal representation of Srtp cryptos from string to int.

Revert of Convert internal representation of Srtp cryptos from string to int. (patchset #10 id:180001 of https://codereview.webrtc.org/1416673006/ )

Reason for revert:
Broke chromium fyi build.

Original issue's description:
> Convert internal representation of Srtp cryptos from string to int.
>
> Note that the coversion from int to string happens in 3 places
> 1) SDP layer from int to external names. mediasession.cc GetSupportedSuiteNames.
> 2) for SSL_CTX_set_tlsext_use_srtp(), converting from int to internal names.
> 3) stats collection also needs external names.
>
> External names are like AES_CM_128_HMAC_SHA1_80, specified in sslstreamadapter.cc.
> Internal names are like SRTP_AES128_CM_SHA1_80, specified in opensslstreamadapter.cc.
>
> The conversion from string to int happens in one place only, SDP layer, SrtpFilter::ApplyParams().
>
> BUG=webrtc:5043
>
> Committed: https://crrev.com/2764e1027a08a5543e04b854a27a520801faf6eb
> Cr-Commit-Position: refs/heads/master@{#10701}

TBR=juberti@webrtc.org,pthatcher@webrtc.org,juberti@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:5043
Committed: https://crrev.com/318166bed75dcbc00a7b79f715f9953aff9ffbc7
Cr-Commit-Position: refs/heads/master@{#10702}

[guoweis_webrtc, 2015-11-19 03:03:15]

Created Revert of Convert internal representation of Srtp cryptos from string to
int.

[commit-bot: I haz the power, 2015-11-19 03:03:28]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1455233005/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1455233005/1

[commit-bot: I haz the power, 2015-11-19 03:03:42]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-11-19 03:03:57]

Patchset 1 (id:??) landed as
https://crrev.com/318166bed75dcbc00a7b79f715f9953aff9ffbc7
Cr-Commit-Position: refs/heads/master@{#10702}