include basepath of parent filename in package.json paths

In addition to any parent paths specified, make sure to check from the
basepath of the parent path.
fix replacing by using module name in browser field

Browser field allows for the module name to be specified as a key. This
means that instances of requiring that module will cause it to be
replaced with the file specified.
0.0.4
node 0.6.x compatibility fix (existsSync)
Merge pull request #9 from thlorenz/master

node0.6.x compatibility fix
make package.json lookups async
add node 0.6 to travis config
add empty file for dgram core module

closes #11
0.0.5
failing test for `false` browser field values
use empty.js target for `false` shims; false test passes
examples
readme example headings
skip example
use tar example for false option
Merge pull request #14 from substack/false

support `false` as a browser field value, added examples
0.1.0
update dependencies: resolve, http, buffer
0.1.1
Change deps source to git