[html] propose html 4 properties (cellPadding ...)

#Issue Type: <b>Bug</b> Cell-padding and cell-spacing, valign and align attribute autocomplete not working VS Code version: Code 1.21.1 (79b44aa704ce542d8ca4a3cc44cfca566e7720f1, 2018-03-14T14:46:47.128Z) OS version: Windows_NT x64 10.0.16299 <details> <summary>System Info</summary> |Item|Value| |---|---| |CPUs|Intel(R) Core(TM) i7-3720QM CPU @ 2.60GHz (8 x 2594)| |Memory (System)|15.93GB (7.93GB free)| |Process Argv|C:\Program Files\Microsoft VS Code\Code.exe| |Screen Reader|no| |VM|0%| </details><details><summary>Extensions (25)</summary> Extension|Author (truncated)|Version ---|---|--- html-snippets|abu|0.2.1 vscode-caniuse|aka|0.5.3 vs-code-css-comments|ash|1.0.3 htmltagwrap|bra|0.0.7 php-autocomplete|bsc|0.4.2 simple-react-snippets|bur|1.1.1 vscode-css-modules|cli|0.2.2 jshint|dba|0.10.17 vscode-eslint|dba|1.4.8 vscode-quick-select|dba|0.2.5 auto-rename-tag|for|0.0.15 auto-comment-blocks|kev|1.0.1 expand-region|let|0.1.2 node-debug2|ms-|1.22.0 sublime-keybindings|ms-|3.0.3 team|ms-|1.122.0 sass-indented|rob|1.4.8 vscode-idiomatic-css-comments|rya|0.1.2 git-autoconfig|shy|0.0.1 easysass|spo|0.0.6 css-auto-prefix|spo|0.1.4 vscode-jss-snippets|vis|0.2.2 vscode-react-native|vsm|0.6.6 html-css-class-completion|Zig|1.17.1 vscode-open-in-github|ziy|1.3.1 (2 theme extensions excluded) </details> Reproduces only with extensions <!-- generated by issue reporter -->