Add gitignore, update guzzle http and remove some unnecessary package

Author: deviddev

Diff for: .gitignore

@@ -0,0 +1,5 @@
+build
+composer.lock
+docs
+vendor
+coverage

Diff for: composer.json

@@ -26,12 +26,10 @@
         "ext-curl": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "guzzlehttp/guzzle": "^6.2"
+        "guzzlehttp/guzzle": "^7.0.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^4.8",
-        "squizlabs/php_codesniffer": "~2.6",
-        "friendsofphp/php-cs-fixer": "~1.12"
+        "phpunit/phpunit": "^4.8"
     },
     "autoload": {
         "psr-4": { "Swagger\\Client\\" : "lib/" }