Improvements on the MongoDB panel

Hi, I've made a few improvements to the interface of the MongoDB panel. Below some screenshots and commit message. Hope you enjoy.

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Sidebar:

![sidebar](https://f.cloud.github.com/assets/1233439/165263/1fb92470-7930-11e2-9eba-b0b8c1e320b7.png)

Stack trace:

![stack_trace](https://f.cloud.github.com/assets/1233439/165264/2272b10e-7930-11e2-89c3-2ec33a7c7bde.png)

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The sidebar now shows the count and time elapsed for each type of
operation performed: read, insert, update, remove.

Changed some code to better reflect MongoDB terminology. The default
operation is now find, instead of query. Queries table became the Reads
table since it displays finds, counts, commands etc. Also, query is
mostly a relational database term.

Corrected the layout of tables, which now properly occupy 100% width of
their containers.