Add `Dotenv::Environment#apply!`

`#apply` will override any existing environment variables addressing
dotenv#38 and dotenv#57.
Add `Dotenv.overload`

Provides an interface to `Dotenv::Environment#apply`, overriding any
environment variables if they are already set.
Split unsupported Regexp into an optional module

At this point tests are passing in Ruby 1.8.7!
One step towards multiple supporting multiple extensions
Allow for more Environment#load extensions in the future
update changelog
Move variable loading to an extension
Clean up extensions, avoid explosing an extension API for now

I think it would be really interesting eventually to expose this to
other gems, but I’d like to experiment with it internally first.
Merge pull request #77 from bkeepers/extensions

Move variable substitution to an extension
Restrict build status to master branch

Currently the build status badge is shown as failing because of failing tests in a branch. This restricts the build status badge to the master branch only.
Merge pull request #79 from krisleech/patch-1

Restrict build status to master branch
Add a Readme note about adding the gem to the top of Gemfile

[ci skip]
Other gems may use `ENV` vars for initializing their settings.
To ensure they use the correct values, `dotenv-rails` should appear at the top of the Gemfile to be loaded first.
Merge pull request #81 from RKushnir/patch-1

Add a Readme note about adding the gem to the top of Gemfile
Improving Capistrano integration docs

I try to give more highlight to the need of adding the gem to the :production group in the Gemfile
Add Ruby 2.1.0, Rubinius, JRuby to Travis config.  Update deprecated syntax in specs to match the remainder.  Add Rubinius gems to Gemfile.
Making a simpler note on Capistrano integration
Merge pull request #85 from xpepper/master

Improving Capistrano integration docs
Merge pull request #83 from petergoldstein/feature/expand_test_matrix

Travis - Ruby 2.1.0, Rubinius, JRuby
Merge pull request #61 from ecbypi/overload-environment-variables

Overload environment variables
Ruby 1.8 compatibility

All dotenv is Ruby 1.8 compatible but not the capistrano recipes.