Fixes #374

Changes:
- Implementation of `setJavaScript()` and `getJavaScript()` added for manipulating document-level JavaScript.
- Additionally, `resetJavaScript()` and `addJavaScript()` methods added.

See the docblocks for all four methods for the description of their operations.

#374 fixed.
Added Unit tests for Zend_Pdf

Unit tests include:
- Zend_Pdf::getJavascript()
- Zend_Pdf::setJavascript()
- Zend_Pdf::resetJavascript()
- Zend_Pdf::addJavascript()

Added Zend_PdfTest test suite to AllTests.php
Method names fixed for Zend_PdfTest
Merge pull request #375 from adeelnawaz/master

Fixes #374 - Implement Zend_Pdf::getJavascript() and Zend_Pdf::setJavascript()