Fix Monolog error where newer versions does not allow an empty stream
Grammar correction
minor #1056 Grammar correction (okj579)

This PR was submitted for the master branch but it was merged into the 1.2 branch instead (closes #1056).

Discussion
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Grammar correction

Commits
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2900425 Grammar correction
allowed any Symfony 2.x versions
fixed tests for Symfony 2.6+
simplified the build matrix
minor #1057 allowed any Symfony 2.x versions for Silex 1.2 (fabpot)

This PR was merged into the 1.2 branch.

Discussion
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allowed any Symfony 2.x versions for Silex 1.2

As we know that Symfony 3.0 will be next year, let's allow any Symfony 2.x versions. I've added the 2.6 and 2.7 versions in Travis to check that everything work fine for all supported Symfony 2.x versions.

Commits
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a5dd2b5 simplified the build matrix
ec53f07 fixed tests for Symfony 2.6+
288d891 allowed any Symfony 2.x versions
fixed CS
fixed some tests
Merge branch '1.2'

* 1.2:
  fixed some tests
  fixed CS
  simplified the build matrix
  fixed tests for Symfony 2.6+
  allowed any Symfony 2.x versions
  Grammar correction

Conflicts:
	composer.json
	tests/Silex/Tests/Application/UrlGeneratorTraitTest.php
	tests/Silex/Tests/Provider/ValidatorServiceProviderTest.php
fixed tests for PHP 5.3
Merge branch '1.2'

* 1.2:
  fixed tests for PHP 5.3

Conflicts:
	tests/Silex/Tests/CallbackServicesTest.php
bug #1046 Fix Monolog error where newer versions does not allow an empty stream (henrikbjorn)

This PR was merged into the 2.0.x-dev branch.

Discussion
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Fix Monolog error where newer versions does not allow an empty stream

Fixes an error with Monolog, only problem is that i think i have already done this PR once before, but it have gone missing.

Commits
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26c7d59 Fix Monolog error where newer versions does not allow an empty stream
fixed CS
removed support for Symfony 2.3 (wrong merge)
Change closures to use $app as the first parameter.

Almost always the first parameter is $app therefor it makes little sense
to use `use` part of the closure and having PHP do context switching all
over the place.

This also makes it explicit in the service providers exactly what $app
instance is used.
no need to do this anymore