Use remotePhpBinaryPath when run composer

[bopoda]

On some shared hostings, we have to use the specified path for PHP binary because of just php can be an outdated version. For example:

-bash-4.1$ which php
/usr/bin/php
-bash-4.1$ php -v
PHP 7.0.21 (cli) (built: Aug 21 2017 17:45:33) ( NTS )
-bash-4.1$ /opt/php71f/bin/php -v 
PHP 7.1.19 (cli) (built: Jul  4 2018 10:51:26) ( NTS )

If composer.json requires php 7.1+, then function doInstallDependencies will fail because of composer check interpeter version. doInstallDependencies generates the command:

/storage/home/srv115367/admin.dom-nf.ru/composer.phar install --no-dev --prefer-dist --no-interaction --quiet

composer install command is executed without specified php interpeter:

Executing command: (export APP_ENV=prod; cd /storage/home/user/project/releases/20190418164853 && /storage/home/user/project/composer.phar install --no-dev --prefer-dist --no-interaction --quiet)

So composer install will fail in this case with the error like:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - This package requires php ^7.1.3 but your HHVM version does not satisfy that requirement.
  Problem 2
    - Installation request for doctrine/annotations v1.6.0 -> satisfiable by doctrine/annotations[v1.6.0].
    - doctrine/annotations v1.6.0 requires php ^7.1 -> your PHP version (7.0.21) does not satisfy that requirement.

In this PR I suggest running composer with specified remotePhpBinaryPath.

ref #90

[fd6130]

Nice one, love this PR. Going to merge it to my fork.