Update change log and spec for wrt-plugins-tizen_0.4.50

Update change log and spec for wrt-plugins-tizen_0.4.50

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

[Issue#] N/A
[Problem] There are including of unused files.
[Solution] Removed including of unused files.
[SCMRequest] N/A

[Issue] N/A
[Problem] updateMessages for email service bug fix
[Cause] updateMessages for email service bug fix
[Solution] updateMessages for email service bug fix

[Issue] N/A
[Problem] Dereferencing pointer "soundPath"
[Cause] Null-checking "soundPath" suggests that it may be null, but it has already been dereferenced on all paths leading to the check
[Solution] inserted Null check.

[Issue] prevent CID : 63078
[Problem] memory leak.
[Cause] free omission.
[Solution] memory free.

[Systeminfo] Fix bug when get duid value

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