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