Use semver for development version

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
Release v0.9.3
Bump to v0.9.4-dev
Make release instructions clearer
mix archive version # & -o flag for #1284
Add Enum.reject

Enum.reject returns elements of collection for which `fun` returns false.
Merge pull request #1321 from guilleiguaran/enum_reject

Add Enum.reject
Allow a record to import itself, closes #1319
Improve error message and optimize record macros
Improve doctest error messages, closes #1318
Fix unused variable warning
Remove useless assignment on defrecord
Tests on windows now intercept stderr from elixir(c) invocations

Previously tests on windows did not intercept stderr when they were
invoked through :os.cmd, so we now add a piper redirect from stderr
to stdout when invoking elixir(c) on windows.
Grouped some windows functionality in test_helper for elixir
Cleaned up the elixir test_helper.exs a bit
Merge pull request #1322 from ToJans/master

Tests on windows now intercept stderr from elixir(c) invocations
Cleaned up test_helper some more
Skip windows test for CHMOD 777, as this does not work on windows
Merge pull request #1323 from ToJans/master

Skip windows test for CHMOD 777, as this does not work on windows
Ensure binding(..., false) also works