Update change log and spec for wrt-plugins-tizen_0.4.51

Update change log and spec for wrt-plugins-tizen_0.4.51

[model] REDWOOD
[binary_type] PDA
[customer] OPEN

[Systeminfo] Change get Sim value code

[Issue] N/A
[Problem] UTC_download_start_P_001 is failed.
[Cause] Using invalid destination virtual path
[Solution] Uses valid path

[WebSetting] Fix websetting privilege TCT issue as well as indentation adjustment.

[Issue] N/A
[Problem] usleep was not decleared
[Cause] unistd.h was missing
[Solution] including unistd.h

[Issue] N/A
[Problem] stopSync fail after sync called quickly
[Cause] stopSync cannot get handle from email service
[Solution] retry to get handle from email service

[Issue#] DCM-2166
[Problem] N/A
[Cause] Internal bug
[Solution] modify code

[Issue#] N/A
[Problem] N/A
[Cause] Internal bug
[Solution] modify code

[team] WebAPI
[request] N/A
[horizontal_expansion] N/A

UnitTC passed.