Improve log/tag search - Githubissues

Currently, log searches are using key:value pairs, with the following characteristics:

API
- One needs to know the keys logs are emitted under
- Multivalue log search can be problematic for services that emit a lot of trace data because of the Cassandra limit problem (#166)
- Logs may only be searched for a particular service. There is no way of combining logs from multiple services.
- Fuzzy matching of logs is limited to wildcard search per log key
- No notion of what amount of data was searched, and what amount was matched.
UI
- On search hits, the entire trace is retrieved, and it's often unclear on which log was matched, or where the match resides on the trace.
- No easy way of identifying how to search logs
- No easy way of narrowing time windows for search

As logs are stored as tags, all of the above apply to tags as well.

jaegertracing / jaeger