Remove deep linking / sub-path parsing

[lidel]

Concern

iiuc the only reason for parsing sub-paths was special-casing during redirects.

Given that we will be removing that special-casing (#16) there is no reason for DNSLink libraries to care about the value after dnslink=/foo/..

Additionally, the way path is parsed in dnslink-std/test v0.9.0 forces everyone to use URL abstractions (pathname, search are URL components that could conflict with characters used as content identifiers)

Ask

Remove sub-path parsing and keep any sub-path as part of the identifier:

dnslink=/<namespace>/<identifier>

## Example
dnslink=/ipfs/QmX2KTMXiUb6tHTMS1JynhyQaL9qoj6uf1SLzHPhzGNnDv/go-ipfs/v0.9.1
namespace=ipfs
identifier=QmX2KTMXiUb6tHTMS1JynhyQaL9qoj6uf1SLzHPhzGNnDv/go-ipfs/v0.9.1

[martinheidegger]

Closed by 4c6ffdc8624d75055ec43e72799059a1319ee0ac