"Loose Typing" section: Several grammatical fixes

Replaced “Web 2.0-ish applications” with “modern web applications”,
hyphenated terms like “back-end” and “client-side”, fixed typo
pertaining to pool metaphor.
"Patterns" section: Rephrased section lead-in
Merge pull request #81 from stackptr/latest

Fixed phrasing and grammar in Loose Typing and Patterns sections