std/rt: in-progress file io work

std: remove unneeded field from RequestData struct

std: rt::uv::file - map us_fs_stat & start refactoring calls into FsRequest

std: stubbing out stat calls from the top-down into uvio

std: us_fs_* operations are now by-val self methods on FsRequest

std: post-rebase cleanup

std: add uv_fs_mkdir|rmdir + tests & minor test cleanup in rt::uv::file

WORKING: fleshing out FileStat and FileInfo + tests

std: reverting test files..

refactoring back and cleanup...
merge cleanup
std: adding file::{stat,mkdir,rmdir}, FileInfo and FileReader/FileWriter

add ignores for win32 tests on previous file io stuff...
std: win32 os::env() str parsing to str::raw::from_c_multistring + test
std: clean up Dir/FileInfo inheritence and flesh out Dir Info
std: more work on from_c_multistring.. let it take an optional len param
std: expose more stat info
std: bind uv_fs_readdir(), flesh out DirectoryInfo and docs/cleanup
std: unignore some file io tests that work on windows, now
std: correctly pass STDOUT in to naive_print test fn
std: generlize & move io::file::suppressed_stat to io::ignore_io_error
std: remove impl'd/commented-out fstat signatures
std: FsRequest.req_boilerplate() be &mut self
std: lots of docs for std::rt::io::file

i hope they don't bitrot
std: minor cleanup in some io_error descs in io::file
std: docstring fixes in io::file
std: merge conflict cleanup from std::str
std: remove RtioStream
auto merge of #9235 : olsonjeffery/rust/newrt_file_io_1, r=alexcrichton

A quick rundown:

- added `file::{readdir, stat, mkdir, rmdir}`
- Added access-constrained versions of `FileStream`; `FileReader` and `FileWriter` respectively
- big rework in `uv::file` .. most actions are by-val-self methods on `FsRequest`; `FileDescriptor` has gone the way of the dinosaurs
- playing nice w/ homing IO (I just copied ecr's work, hehe), etc
- added `FileInfo` trait, with an impl for `Path`
  - wrapper for file-specific actions, with the file path always implied by self's value
  - has the means to create `FileReader` & `FileWriter` (this isn't exposed in the top-level free function API)
  - has "safe" wrappers for `stat()` that won't throw in the event of non-existence/error (in this case, I mean `is_file` and `exists`)
  - actions should fail if done on non-regular-files, as appropriate
- added `DirectoryInfo` trait, with an impl for `Path`
  - pretty much ditto above, but for directories
  - added `readdir` (!!) to iterate over entries in a dir as a `~[Path]` (this was *brutal* to get working)

...<del>and lots of other stuff</del>not really. Do your worst!