Initial commit
Implementation of pulse and cmd/pulsecli.

* supports build triggering by project name matching
* supports health checks, which fails when:
  - at least one agent is off-line
  - at least 50% of agents are in Synchronizing state
Implement tests for pulse/client.
pulse: Add WaitBuild method
pulse: Add Pending()

Pending() method is a fix for nightly builds, during which tests can't
expect every build trigger will go immadiately without waiting for an
agent.
pulse/pulsecli: Refactor cmd/pulsecli into separate testable package
pulse: Add Readme.md
Update Readme.md
Update Readme.md
pulse: Add LatestBuildResult
cmd/pulsecli: Add status command
Move pulse/ to pulseutil/

Conflicts:
	Readme.md
Update Readme.md
pulsecli: Fix handling build offsets for the status command
pulseutil: Change import paths
pulsecli: Add --prtg flag
cmd/pulsecli: Add session management
pulsecli: Fix go vet warnings
pulsecli: Improve output for agents and trigger subcommands
pulsecli: Add build subcommand