Updated dependencies listed in README.md
Clarified dependencies in README.md
Added variable for ttrss version.
Updated shebang to bash.

Using bin/sh utilizes the outdated shell, which does not support the
`echo -e` command. This results in -e being echoed throughout the script
instead of being interpreted as a flag.
Fixed typo.
Caught another typo.
Utilizing heroku's native support for mbstring

Heroku already supports the mbstring extension, but it is disabled by
default (https://devcenter.heroku.com/articles/php-support#extensions).
We merely need to activate it via the composer.json file. There is no
need to add mbstring support via a third party source.
Added disclaimer for Mac OSX sed in README.md
Updated php/apache locations.
Removed nonworking sh heroku-php-apache2.
Removed unnecessary verbosity of tar command.
Fixed web-boot.sh creation and push to heroku.
Added forgotten commit before pushing.
Fixed Procfile and web-boot.sh with forgotten info
Clarified installation of GNU sed
There's no php.ini file in the home directory.
Pushed procfile/web-boot with initial push.

Currently, Procfile and web-boot.sh are pushed after an initial empty
commit/push, which is unnecessary and causes the dyno to restart twice,
taking up extra time. This pushes the Procfile and web-boot.sh with the
initial push.
Removed tracking with the origin GitHub.

Currently, the script does not remove the origin remote, resulting in
confusion where the repo is in sync with heroku but complains about
"Your branch is ahead of 'origin/master' by 2 commits." Removing origin
altogether removes this confusion, and it is unlikely that the user
would want to push their ttrss installation to the GitHub origin anyway.
Merge pull request #11 from jkdf2/master

Update ttrss with heroku changes and improve some logic.