wip
bolt db works
add travis deps
save horizon with transactions
fix all iterator
port 117 fix to bolt
slight improvement by appending deltas first
Merge branch 'master' into bolt_json
117 patched in
Merge branch 'log_database' into boltdb
store less duplicate data in the indices
Merge branch 'master' into boltdb
concrete deltas
improve cost of bolt iterator
Merge branch 'master' into boltdb
Merge branch 'master' into boltdb
Move flag handling out of config into main

This places all the flag definitions together, making them easier to
find, and makes it possible (in the future) to use db for convenience
functions when we have a Go API, without having flag space contaminated
by cayley main flags.
Clean up usage

* Use raw strings.
* Hook usage into flag.
* Print banner to stderr as flag.PrintDefaults does.
* Use the cayley usage rather than the flag ussage when command is
  unknown.
* Simplify args handling.
Make usage cayley intro banner contextual

Only provide it when people run cayley without any other args.
Move remove() and removeAll() to tests

This is done to keep deadcode quiet.