publish: use generic queries

Use generic queries instead of specialized index queries. This is a step
towards the publisher app, because its client will have to use generic
queries.

Context: http://camlistore.org/issue/365

Change-Id: I2781a345e024174e3bea8511b6cdc6f342d5a7c1
Merge "publish: use generic queries"
search: accept 'and', 'or', and parentheses in expressions

'and' has precendence over 'or'.
both operators are left associative
parenthesized expressions are evaluated first
Parser refactored, parseAtom split up.

Change-Id: I1f194cc75df49bad9d30d041d689d8ba833076f1
TODO: clean up sync+index incoming blob handling

Change-Id: I64cd4818dead81f5a0dac0e275994df17b7740ef