Split of Sinks to address #88

[merbla]

• Core in Serilog.Sinks.Splunk
• HEC inSerilog.Sinks.Splunk
• TCP in Serilog.Sinks.Splunk.TCP
• UDP in Serilog.Sinks.Splunk.UDP
• Waiting on #65 for cross plat from Splunk.Logging.Common

Versions TBD.

[merbla]

Currently versions using

• Serilog.Sinks.Splunk (3.0)
• Serilog.Sinks.Splunk.TCP (1.0)
• Serilog.Sinks.Splunk.UDP (1.0)

[merbla]

Merging to test the multi package build/release.