Continue scraping old targets on SD fail.

When we have trouble resolving the targets for a job via service
discovery, we shouldn't just stop scraping the targets we currently
have.
Merge pull request #328 from prometheus/scrape-old-targets-on-sd-fail

Continue scraping old targets on SD fail.
Completely extract response payload for decoding.

This commit forces the extraction framework to read the entire response payload
into a buffer before attempting to decode it, for the underlying Protocol Buffer
message readers do not block on partial messages.
Merge pull request #331 from prometheus/fix/retrieval/payload-extraction-buffering

Completely extract response payload for decoding.
Represent targets in a tabular interface.

This commit represents a target group's endpoints in a tabular fashion for better differentiation
of their state in a concise manner.
Code Review: Formatting comments.
Merge pull request #330 from prometheus/feature/interface/tabular-targets

Represent targets in a tabular interface.
Round time to nearest second in memory storage.

When samples get flushed to disk, they lose sub-second precision anyways. By
already dropping sub-second precision, data fetched from memory vs. disk will
behave the same. Later, we should consider also storing a more compact
representation than time.Time in memory if we're not going to use its full
precision.
Merge pull request #333 from prometheus/round-time

Round time to nearest second in memory storage.
Replacing interface components with Bootstrap.

This commit includes Bootstrap 2.3.2 and swaps a multitude of graph,
status, and other components to Bootstrap-based widgets.

P.S. - Sabra fucking rocks!