Fix deprecated octal syntax

refs
elixir-lang/elixir#2598
elixir-lang/elixir@6874eb7ce8bb89c74abe6819bed994cb776bf397
Merge pull request #312 from niku/octal-syntax

Fix deprecated octal syntax
Update to v0.15.0
Use String.to_integer/1
Add links to mailing list and issues tracker
v0.15.0 announcement
Link to Windows installer
Add Elixir Web Installer notes to the post
Incorporate @alco feedback
Merge pull request #314 from elixir-lang/jv-0-15-0

v0.15.0 announcement
Fixes to the announcement
Typo

s/funcionality/functionality/
Merge pull request #315 from grempe/patch-1

Typo
Release v0.15.1
Fix typos.
Merge pull request #316 from ideal-knee/fix-typos

Fix typos.
Update installer links
Add a note about using different machines
Fixed typo.

manualy => manually
Merge pull request #318 from leighlondon/spelling

Fixed typo.