Introduced new voicemail fields in 'calls' table.

The 'calls' table is going to be shared between the existing call_log
provider, and to be added voicemail provider. This change adds all the
columns needed to support voicemail in the 'calls' table.

The call_log provider, however, uses only one additional field
'voicemail_uri', whereas all other new fields will exclusively be used the
new voicemail provider. The change also ensures that the voicemail
provider specific fields are not exposed through the call_log provider.

Change-Id: Ieea4b14052b7e7e9db0e674138772b4e06b3f074
6 files changed