updated pdf viewer
i18n: Fix the chinese name of chinese language

The current version of chinese language's chinese name is not political neutral.
In fact, which form of chinese (traditional or simplified) can be called "正體"(in traditional chinese) or "正体"(in simplified chinese) is not globally defined.
So, I change the name according to the word used by Microsoft Windows, which is more neutral.
Update course_about.html

if course title use Chinese or other language got the 500 error when visit the course_about page ,and the log shows :UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-3: ordinal not in range(128)
Update reference to the xblock-mentoring repo for optimized dataexport

The new ref is gsehub/xblock-mentoring@43aa320

Optimize mentoring-dataexport times by using values_list()
Add some optional policies around password resets, such as password reuse, forced password resets, allowed frequency of password resets
password history: just limit the result set range to simplify iteration logic
Update translations (autogenerated message)
Added note about pages being publicly viewable

STUD-1488
Upgrade JSdraw input.
Transcript translations should be displayed in their source language.
Fix tests.
Revert "Fix tests."

This reverts commit 1ed167d90a99c8f5d5884c9300a69ca5a7cc1d92.
Revert "Transcript translations should be displayed in their source language."

This reverts commit b4ba04bae9e3d44be92e6f870be5b80e9f464878.
Merge pull request #3088 from fmyzjs/patch-3

Update course_about.html
moved Studio public Pages warning to a more prominent location
Merge pull request #3107 from FiloSottile/optimize_dataexport

Update reference to the xblock-mentoring repo for optimized dataexport
Merge pull request #3130 from edx/sarina/033114-language-update

Update translations (autogenerated message)
Added comment to getUserMedia call in photocapture.js
Merge pull request #3054 from louyihua/fix-chinese-language-name

Fix the chinese name of chinese language in common.py
Translation fix in studio: For better translation

As the sentence in unit.html is splitted into three parts due to the varible release_date may be None, it breaks the integrity of a sentence.
Different language may have different word or event grammer order, so if a sentence is breaked into three parts, translators cannot adjust the word orders to create a good translation.
So this fix tries to combine the sentence together.