0Net HTML functional problems tourgh the browser

### Step 1: Please describe your environment

* ZeroNet version: 0.6.5 (Rev: 3866)
* Operating system: Windows 10
* Web browser: Firefox Quantum 69.0.3
* Tor status: always
* Opened port: no
* Special configuration: Trackers goes tourgh TOR

### Step 2: Describe the problem:

Some HTML problems when a user setup a single user site tourgh 0Net and open the current zite the browser.

#### Steps to reproduce:

1. 0hello Files page .mp4 files are not played (no supported mime video).But tourgh HTML5 player are working perfectly the same files.
2. http ://127.0.0.1:43110/site/folder /some video file.mp4 as link in a website not played
3. Images and video and somethingéáüö.html files not accept special characters in HTML files Example:

bnhméűo.jpg i get:
Server error
Err: UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 4: ordinal not in range(128) in UiServer.py line 103 > UiRequest.py line 152 > UiConfigPlugin.py line 21 > ContentFilterPlugin.py line 193 > UiRequest.py line 371 > UiRequest.py line 470 > FilePackPlugin.py line 108 > SiteStorage.py line 349 > SiteStorage.py line 368
4. Opening new site in a new tab using the target="_blank command are not loading the page.

Some zite open new tab
5. Not possible to automatic way easy download all optional large files in a single user zite when the user download the site.So large files are not seeded.
6. .SWF game or another files are not working.
7. All files only sows correctly with UTF-8 format.
8. User can not go back using the browser back button if he open another zite to the previous zite.
9. Can not go back the previous page in zites when the user click the back button in the browser the user stuck in the same page.This can be a problem for larger pages.