Swap "Merge Request" and "Branches" tabs in branch view in WebIDE
### Summary When viewing a branch in Web IDE, especially one, connected to a merge request, we show dropdown above branch files in the left panel in the format: ``` branch-name | merge-request-id ``` Though when one clicks this dropdown to get a lit of all branches or all merge requests on this project, the order of the tabs in the dropdown is reversed: ``` merge-requests-list | branches-list ``` that is a bit confusing ![Screenshot_2019-03-01_at_22.07.35](/uploads/d0a88c7d2dccb69d2485e6c4fd792bba/Screenshot_2019-03-01_at_22.07.35.png) ### Possible fixes I this we should swap panels in the dropdown to follow the `branch -> merge request` pattern
issue