Encode BulletSpan in toHtml() conversion

Changes in toHtml() conversion with TO_HTML_PARAGRAPH_LINES_INDIVIDUAL:

- Wrap each paragraph inside a block-level element
Each paragraph delimited by '\n' is now wrapped individually inside either
a <p> or a <li> block to allow per-paragraph formatting.

- Wrap paragraphs covered by BulletSpans as <li> instead of <p> blocks

- Encode text alignment at paragraph level
Instead of creating <div> blocks outside of the block quote level.

- Encode AlignmentSpan as CSS style instead of the ALIGN attribute
The ALIGN attribute is obsolete.

Change-Id: I3a8b315224b762af99eda69cb19f5cf6b3f05dac