Bug 1093929 - Improve grunt tasks and add additional options

nit: replaced nogit with unknown

Fixed nits and update README

Fixed dev server value in config.js

Fixed review comments

Add build folder to .gitignore

Addressed review comments
Bug 1082517 - Remove ensureGUM call before opening the attention screen
Merge pull request #288 from dcoloma/grunt-changes

Bug 1093929 - Improve grunt tasks and add additional options r=jaoo
Bug 1099023 - [Loop] First Loop call shows the call status bar on bottom
Merge pull request #304 from AntonioMA/bug1082517

Bug 1082517 - Remove ensureGUM call before opening the attention screen
Merge pull request #306 from crdlc/bug-1099023

Bug 1099023 - [Loop] First Loop call shows the call status bar on bottom
Bug 1098407 - Need to adapt FxOS Loop client to send the MCC of the caller (follow up bug 1039444). r=borjasalguero