Fix sagan-client build issues under Windows

Prior to this commit, sagan-client npm build would fail under Windows.
This commit:

* uses a specific command for Windows systems when launching NPM tasks
* upgrades gulp-cram to fix a path relative issue
* upgrades various sagan-client dependencies

See #336
Consolidate table styles with guides

This commit import additional CSS rules from markdown-content.css into
blog posts. This brings better table headers and margins before/after
tables.
Update language level from 1.7 to 1.8
Replace explicit types with <> (main)
Replace explicit types with <> (test)
Use lambda expressions where possible (main)
Use lambda expressions where possible (test)
Replace external iteration with stream API (main)
Replace external iteration with stream API (test)
Fix Profile name typo in comment
Merge pull request #349 from bparry02/patch-1

Fix Profile name typo in comment
Revert "Work around gradle dist zip download error"

This reverts commit c96b799216bb0c9b44adb40be840c819a672dffd.
Hide clipboard button to improve code readability

The "copy to clipboard" button is now hidden when the pointer is not
over the code examples.
Merge pull request #347 from bclozel/sagan-347

Fix table style in blog posts
Merge pull request #345 from bclozel/sagan-345

Fix npm commands tasks under Windows
Merge pull request #340 from bclozel/sagan-340

code-snippet copy button covers content in top-right corner
Merge pull request #348 from spring-io/jdk8-lang

Use JDK 8 language features
Set Eclipse/STS JDT to 1.8 compliance

See: #181
Sync wiki submodule
Upgrade to Spring Boot 1.0.2 GA

Resolves #364