Fix indenting of HTML tags for instance. Fix #1294

Commit Summary
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If you press ENTER before a line, a new line is introduced by appending "\n" before it.
Therefor a previous line of "" is appended before the <TAG>-line.
This line remains unindented, causing a wrong indentation for the next line.
Basically this is fixed by indenting this line (oldBuffer.end.row = newBuffer.start.row).

Bug Description
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As in #1294: If you put the cursor before a tag and press ENTER the indentation get's messed up.

Current Behavior
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![current_behavior](https://cloud.githubusercontent.com/assets/1194855/2938230/e0334d08-d8fb-11e3-80f3-3896fdc44896.gif)

Expected (Fixed) Behavior
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![fixed_and_expected_behavior](https://cloud.githubusercontent.com/assets/1194855/2938232/075e9018-d8fc-11e3-925a-34176bcaae63.gif)