Update xterm.js to the newer version.

[AndrienkoAleksandr]

It make sense to update xterm.js terminal to the newer version. Very soon (about one-two weeks or even less) will be released xterm.js 3.0.

https://github.com/xtermjs/xterm.js

[AndrienkoAleksandr]

Needed for:
eclipse-che/che#7029
eclipse-che/che#5084
eclipse-che/che#4315

[AndrienkoAleksandr]

Created CQ for xterm.js 3.1.0: https://dev.eclipse.org/ipzilla/show_bug.cgi?id=15710

[AndrienkoAleksandr]

CQ xterm.js 3.1.0: https://dev.eclipse.org/ipzilla/show_bug.cgi?id=15710 closed;
CQ xterm.js Version: 3.3.0 approved: https://dev.eclipse.org/ipzilla/show_bug.cgi?id=16190 .

[AndrienkoAleksandr]

In progress.