Improve UI for browsers

[vitonsky]

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I like to use this tool, but web UI are disgusting. On my mobile device text looks ridiculous small and progress bar absolutely useless. Let's improve it.

Changes that i suggest to

• replace <meta name="Airshare Upload" content="width=device-width, initial-scale=1.0"> to a <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
• instead of one loader that just blink and inform users about nothing - render loading status in percents for each file. You may use javascript XMLHttpRequest API to implement it