[CLEANUP] Rename the Tests/ directory to tests/ (#265)

This is the first step towards adopting more of the default
Symfony project structure.

Author: oliverklee

.github/CONTRIBUTING.md

@@ -59,28 +59,28 @@ script:
 - >
   echo;
   echo "Linting all PHP files";
-  find Classes/ Tests/ web/ core/ -name ''*.php'' -print0 | xargs -0 -n 1 -P 4 php -l; php -l bin/*;
+  find Classes/ tests/ web/ core/ -name ''*.php'' -print0 | xargs -0 -n 1 -P 4 php -l; php -l bin/*;
 
 - >
   echo;
   echo "Running the unit tests";
-  vendor/bin/phpunit -c Configuration/PHPUnit/phpunit.xml Tests/Unit/;
+  vendor/bin/phpunit -c Configuration/PHPUnit/phpunit.xml tests/Unit/;
   vendor/bin/phpunit core/tests/;
 
 - >
   echo;
   echo "Running the integration tests";
-  vendor/bin/phpunit -c Configuration/PHPUnit/phpunit.xml Tests/Integration/;
+  vendor/bin/phpunit -c Configuration/PHPUnit/phpunit.xml tests/Integration/;
 
 - >
   echo;
   echo "Running the system tests";
-  vendor/bin/phpunit -c Configuration/PHPUnit/phpunit.xml Tests/System/;
+  vendor/bin/phpunit -c Configuration/PHPUnit/phpunit.xml tests/System/;
 
 - >
   echo;
   echo "Running the static analysis";
-  vendor/bin/phpstan analyse -l 5 bin/ Classes/ Tests/ web/;
+  vendor/bin/phpstan analyse -l 5 bin/ Classes/ tests/ web/;
 
 - >
   echo;
@@ -90,4 +90,4 @@ script:
 - >
   echo;
   echo "Running PHP_CodeSniffer";
-  vendor/bin/phpcs --standard=Configuration/PhpCodeSniffer/ bin/ Classes/ Tests/ web/;
+  vendor/bin/phpcs --standard=Configuration/PhpCodeSniffer/ bin/ Classes/ tests/ web/;

.github/PULL_REQUEST_TEMPLATE.md

@@ -68,7 +68,7 @@
     },
     "autoload-dev": {
         "psr-4": {
-            "PhpList\\PhpList4\\Tests\\": "Tests/"
+            "PhpList\\PhpList4\\Tests\\": "tests/"
         }
     },
     "scripts": {
@@ -97,7 +97,7 @@
         "symfony-bin-dir": "bin",
         "symfony-var-dir": "var",
         "symfony-web-dir": "web",
-        "symfony-tests-dir": "Tests",
+        "symfony-tests-dir": "tests",
         "phplist/phplist4-core": {
             "bundles": [
                 "Symfony\\Bundle\\FrameworkBundle\\FrameworkBundle",