Update build deps

Fixes https://crosswalk-project.org/jira/browse/XWALK-1911
Merge pull request #140 from crosswalk-project/build-deps-1911

Update build deps
[remote debugging] Merge wiki info

Merge information from the wiki page about remote debugging:

https://crosswalk-project.org/#wiki/Remote-Debugging-on-Android

into the main website.

Fixes https://crosswalk-project.org/jira/browse/XWALK-2167
Merge pull request #141 from crosswalk-project/remote-debug-2167

[remote debugging] Merge wiki info
Bump stable and beta versions to 7 and 8 respectively
[WebRTC] Use stable version macro instead of hard-coding

Ensure that the version of Crosswalk referenced is the current
stable version, rather than hard-coding it to version 6.
Use a custom gollum with Thin server to improve performance

This makes it easier to tell when gollum is or isn't available
(I can properly track the pid using a file), reduces the gollum
start up time (by a factor of 10), and slightly improves the time
taken for translating mark-up to HTML (mainly because the HTTP
requests return slightly faster).
Merge pull request #142 from crosswalk-project/gollum-improvements

Use a custom gollum with Thin server to improve performance
[manifest] Update for xwalk_launch_screen
[manifest] Crosswalk 8 on Android supports start_url

app.launch.local_path is deprecated on Crosswalk Android 8+
[manifest] csp replaces content_security_policy
[manifest] Make room for orientation page
[manifest] Make field-description page titles consistent
[manifest] Ensure fields are correct for Crosswalk 8
[manifest] Add xwalk_permissions field
[manifest] Flesh out orientation description and page
[manifest] Add W3C-compatible 'icons' field
Remove detail about screen measurement from icons page
Rearrange JSON file order for consistency

*.extension comes after the spec-compatible field in the JSON file.
Update fields in line with comments on XWALK-2131 so far