Unnecessary tracking of lock file

The `composer.lock` file locks versions of software together, but it is
only relevant to aplications. For libraries, the version declaration
needs to be specific so applications may not consume it in a way it was
not supposed to work on.

Does some house cleaning by providing a proper continuous integration
suite to the whoe thing. The `phpunit.xml.dist` move was made so running
phpunit on the root folder (where most people like to work from) would
use *by default* a configuration file, also ignores the user
`phpunit.xml` so anyone may have rights to their own opinion.

Ignoring the `*.swp` (VIM swap files) is just something I am doing to
teach a fellow user in arms how good can it be to *git globally ignore*
swap files and such. I even had to hear, silently - which typing this
very message on a foreign keyboard, to go on and ignore `*.sw*` all the
way. Hopefully, now, he understands something more.... I hope that it is
how valuable commits can be. ;)

XOXO

PS: You are welcome for the `git add -p`.

.gitignore

@@ -1 +1,4 @@
+*.lock
+*.swp
 vendor
+phpunit.xml

.travis.yml

@@ -0,0 +1,11 @@
+language: php
+php:
+  - '5.4'
+  - '5.5'
+  - '5.6'
+  - '7.0'
+  - '7.1'
+  - nightly
+
+before_script: composer install
+script: composer test

composer.json

@@ -1,20 +1,28 @@
 {
-    "name": "iannsp/Ngram",
-    "description": "A n-gram toolset.",
-    "require-dev": {
-        "phpunit/phpunit": "~4.4"
-    },
-    "license": "GPL-3.0+",
-    "authors": [
-        {
-            "name": "Ivo Nascimento",
-            "email": "[email protected]"
-        }
-    ],
-    "require": {
-        "html2text/html2text": "*"
-    },
-    "autoload": {
-        "psr-4": {"Ngram\\": "src/Ngram/"}
-    }
+	"name": "iannsp/ngram",
+	"description": "A n-gram toolset.",
+	"license": "GPL-3.0+",
+	"authors": [
+		{
+			"name": "Ivo Nascimento",
+			"email": "[email protected]",
+			"role": "Author"
+		}
+	],
+	"require": {
+		"php": ">=5.4",
+		"html2text/html2text": "~2.0.1"
+	},
+	"autoload": {
+		"psr-4": {"Ngram\\": "src/Ngram/"}
+	},
+	"require-dev": {
+		"phpunit/phpunit": "~4.4"
+	},
+	"autoload-dev": {
+		"psr-4": {"Ngram\\": "tests/Ngram/"}
+	},
+	"scripts": {
+		"test": "phpunit --verbose"
+	}
 }